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2026-07-07T21:38:54Z
User contributions
MediaWiki 1.46.0
https://medlabwiki.com/index.php?title=Viral_hepatitis&diff=241
Viral hepatitis
2026-06-24T23:28:12Z
<p>Admin: Created page with "Hepatitis A virus * Fecal-oral transmission (foodborne and waterborne transmission) * Highest rates of infection in children (30% of all infections), asymptomatic in 90% of children under 5 years old * Acute onset of symptoms * Usually self-limiting disease with low mortality * Vaccination and immunoglobulin therapy available * Diagnosis by PCR or antibody detection (HAV IgM) Hepatitis B virus Hepatitis C * Has highest mortality rate of all hepatitis viruses * 50% de..."</p>
<hr />
<div>Hepatitis A virus<br />
<br />
* Fecal-oral transmission (foodborne and waterborne transmission)<br />
* Highest rates of infection in children (30% of all infections), asymptomatic in 90% of children under 5 years old<br />
* Acute onset of symptoms<br />
* Usually self-limiting disease with low mortality<br />
* Vaccination and immunoglobulin therapy available<br />
* Diagnosis by PCR or antibody detection (HAV IgM)<br />
<br />
Hepatitis B virus<br />
<br />
Hepatitis C<br />
<br />
* Has highest mortality rate of all hepatitis viruses<br />
* 50% develop to chronic HCV, with 20-30% developing cirrhosis<br />
* Diagnosis <br />
** Recommended to use either point-of-care RNA testing, or a 2-step approach:<br />
** Test for antibody detection (Anti-HCV)<br />
*** Anti-HCV detected in 80% of patients within 6 weeks<br />
*** Anti-HCV detected in 90% of patients within 12 weeks<br />
** If Anti-HCV is positive, perform PCR test<br />
<br />
{| class="wikitable"<br />
|+<br />
!<br />
!<br />
!<br />
!<br />
|-<br />
|Anti-HCV<br />
|Positive<br />
|Positive<br />
|Negative<br />
|-<br />
|PCR<br />
|Positive<br />
|Negative<br />
|Positive<br />
|-<br />
|Interpretation<br />
|Acute or chronic infection<br />
|Past infection or<br />
|Acute or chronic infection<br />
|}<br />
<br />
* Treatment with oral drugs effective in >95% of patients<br />
<br />
Hepatitis D virus<br />
<br />
* 1.7-kb ssRNA virus<br />
* Requires HBV for replication (HBsAg required for virus envelope)<br />
* Transmitted via blood or mucosal contact<br />
* May occur as a result of co-infection of both viruses at the same time, or when someone with chronic HBV is exposed to HDV<br />
* Often results in severe disease, including cirrhosis (66% progress to cirrhosis, with a 5% mortality rate)<br />
* Diagnosis by PCR or antibody detection (HDV IgM and IgG)<br />
<br />
Hepatitis E</div>
Admin
https://medlabwiki.com/index.php?title=Microbiology&diff=240
Microbiology
2026-06-24T23:02:29Z
<p>Admin: </p>
<hr />
<div>[[Microbiology Quick Reference]]<br />
<br />
Theory<br />
<br />
Microbiology Tests<br />
<br />
[[Colony Morphology]]<br />
<br />
== Organisms ==<br />
Gram positive cocci<br />
<br />
Gram positive cocci clusters<br />
<br />
Gram positive cocci pairs and chains<br />
<br />
Gram negative bacilli<br />
<br />
Non-fermenters/other gram negative bacilli<br />
<br />
Gram positive bacilli<br />
<br />
Fastidious gram negatives<br />
<br />
Anaerobes<br />
<br />
Yeasts<br />
<br />
== Virology ==<br />
[[Viral hepatitis]]<br />
<br />
[[Human immunodeficiency virus|Human immunodeficiency virus (HIV)]]<br />
<br />
== Parasitology ==</div>
Admin
https://medlabwiki.com/index.php?title=Interferences&diff=239
Interferences
2026-02-06T01:37:15Z
<p>Admin: /* Specimen Integrity Issues */</p>
<hr />
<div>There are a variety of different factors that can interfere with laboratory results. The following provides an overview of possible interferences.<br />
<br />
== Specimen Integrity Issues ==<br />
<br />
=== Hemolysis ===<br />
Hemolysis can interfere directly with lab results (due to the release of red blood cell components) or indirectly by affecting <br />
<br />
* May be due to patient's condition (e.g., hemolytic anemia, autoimmune conditions, certain drugs, etc.)<br />
* May be due to improper specimen collection (e.g., too much force during venipuncture due to small needle gauge or pulling too hard on syringe, slow draws, excess damage to tissue during venipuncture, excessive mixing, etc.)<br />
<br />
Tests most affected by hemolysis include:<br />
<br />
* Potassium<br />
* ALP<br />
* LDH<br />
* RBC<br />
* Hemoglobin<br />
* Hematocrit<br />
<br />
=== Icterus ===<br />
<br />
=== Lipemia ===<br />
<br />
* Cloudiness of sample due to lipemia affects photometric methods<br />
* May be caused by recent fatty meals or be due to a patient's condition<br />
* Lipemia can be removed by ultracentrifugation of samples<br />
** Do not ultracentrifuge lipid, cholesterol, triglyceride, etc. tests as this removes the fats<br />
<br />
=== Other Factors ===<br />
<br />
* Quantity not sufficient<br />
** Insufficient sample volumes may cause aspiration errors and cause false results<br />
*Clotted specimen<br />
**Serum samples may require 30 minutes or more to fully clot before being centrifuged; the use of clot activators (silica, thrombin, etc.) can reduce the clotting time to about 10 minutes<br />
**If samples are not fully clotted before being spun, they can continue to clot as they are introduced to the analyzer; this can result in aspiration errors or erroneous results due to fibrin strands<br />
**Clots should be removed and samples re-spun before introducing to an analyzer<br />
**Where possible, plasma samples (sodium or lithium heparin tubes) can be used as they contain an anticoagulant to prevent clotting<br />
* Diluted specimen<br />
** Dilution of the specimen can be the result of improper collection (e.g., saline or other products from collection above IV lines) or due to adulteration<br />
** These specimens will generally show decreased results due to a dilutional effect<br />
** Serum/plasma may appear very pale, and the ratio of red blood cells to plasma will be off (significantly more plasma than red blood cells)<br />
** Multiple different results may be affected (e.g., chemistry and hematology results, multiple analytes, etc.)<br />
** Certain tests may be affected more depending on the diluting material<br />
*** Contamination from heparinized lines will falsely prolong coagulation results<br />
*Contaminated specimen<br />
**EDTA contamination<br />
***Due to improper collection order (e.g., collection of lavender top EDTA tubes before chemistry tubes)<br />
****Falsely increased potassium (often >10 mmol/L)<br />
****Falsely decreased calcium (often <0.50 mmol/L), magnesium, and alkaline phosphatase (ALP)<br />
**Lithium heparin contamination<br />
***Falsely increased lithium<br />
***Sodium heparin should be used for samples requiring lithium measurement<br />
*Old or unspun specimens<br />
**The stability of analytes can change as specimens age, especially when red blood cells are not separated from serum/plasma<br />
**Samples should be spun as soon as possible; if a separator gel is not present in the tube, plasma/serum should be aliquoted to a new tube <br />
**Falsely increased potassium (as a major intracellular cation, potassium leaks from red blood cells over time or when cells are damaged)<br />
**Falsely decreased glucose (as glucose is taken up by cells and used for cellular respiration over time as the sample sits)<br />
* Biotin<br />
** Biotin (also known as Vitamin B7, Vitamin H, or coenzyme R) may interfere with biotin-based immunoassays, causing false positive results</div>
Admin
https://medlabwiki.com/index.php?title=Interferences&diff=238
Interferences
2026-02-06T01:33:51Z
<p>Admin: /* Specimen Integrity Issues */</p>
<hr />
<div>There are a variety of different factors that can interfere with laboratory results. The following provides an overview of possible interferences.<br />
<br />
== Specimen Integrity Issues ==<br />
<br />
=== Hemolysis ===<br />
Hemolysis can interfere directly with lab results (due to the release of red blood cell components) or indirectly by affecting <br />
<br />
* May be due to patient's condition (e.g., hemolytic anemia, autoimmune conditions, certain drugs, etc.)<br />
* May be due to improper specimen collection (e.g., too much force during venipuncture due to small needle gauge or pulling too hard on syringe, slow draws, excess damage to tissue during venipuncture, excessive mixing, etc.)<br />
<br />
Tests most affected by hemolysis include:<br />
<br />
* Potassium<br />
* ALP<br />
* LDH<br />
* RBC<br />
* Hemoglobin<br />
* Hematocrit<br />
<br />
=== Icterus ===<br />
<br />
=== Lipemia ===<br />
<br />
* Cloudiness of sample due to lipemia affects photometric methods<br />
* May be caused by recent fatty meals or be due to a patient's condition<br />
* Lipemia can be removed by ultracentrifugation of samples<br />
** Do not ultracentrifuge lipid, cholesterol, triglyceride, etc. tests as this removes the fats<br />
<br />
=== Other Factors ===<br />
<br />
* Quantity not sufficient<br />
** Insufficient sample volumes may cause aspiration errors and cause false results<br />
*Clotted specimen<br />
**Serum samples may require 30 minutes or more to fully clot before being centrifuged; the use of clot activators (silica, thrombin, etc.) can reduce the clotting time to about 10 minutes<br />
**If samples are not fully clotted before being spun, they can continue to clot as they are introduced to the analyzer; this can result in aspiration errors or erroneous results due to fibrin strands<br />
**Clots should be removed and samples re-spun before introducing to an analyzer<br />
* Diluted specimen<br />
** Dilution of the specimen can be the result of improper collection (e.g., saline or other products from collection above IV lines) or due to adulteration<br />
** These specimens will generally show decreased results due to a dilutional effect<br />
** Serum/plasma may appear very pale, and the ratio of red blood cells to plasma will be off (significantly more plasma than red blood cells)<br />
** Multiple different results may be affected (e.g., chemistry and hematology results, multiple analytes, etc.)<br />
** Certain tests may be affected more depending on the diluting material<br />
*** Contamination from heparinized lines will falsely prolong coagulation results<br />
*Contaminated specimen<br />
**EDTA contamination<br />
***Due to improper collection order (e.g., collection of lavender top EDTA tubes before chemistry tubes)<br />
****Falsely increased potassium (often >10 mmol/L)<br />
****Falsely decreased calcium (often <0.50 mmol/L), magnesium, and alkaline phosphatase (ALP)<br />
*Old or unspun specimens<br />
**The stability of analytes can change as specimens age, especially when red blood cells are not separated from serum/plasma<br />
**Samples should be spun as soon as possible; if a separator gel is not present in the tube, plasma/serum should be aliquoted to a new tube <br />
**Falsely increased potassium (as a major intracellular cation, potassium leaks from red blood cells over time or when cells are damaged)<br />
**Falsely decreased glucose (as glucose is taken up by cells and used for cellular respiration over time as the sample sits)<br />
* Biotin<br />
** Biotin (also known as Vitamin B7, Vitamin H, or coenzyme R) may interfere with biotin-based immunoassays, causing false positive results</div>
Admin
https://medlabwiki.com/index.php?title=Interferences&diff=237
Interferences
2026-02-06T01:29:44Z
<p>Admin: /* Specimen Integrity Issues */</p>
<hr />
<div>There are a variety of different factors that can interfere with laboratory results. The following provides an overview of possible interferences.<br />
<br />
== Specimen Integrity Issues ==<br />
<br />
=== Hemolysis ===<br />
Hemolysis can interfere directly with lab results (due to the release of red blood cell components) or indirectly by affecting <br />
<br />
* May be due to patient's condition (e.g., hemolytic anemia, autoimmune conditions, certain drugs, etc.)<br />
* May be due to improper specimen collection (e.g., too much force during venipuncture due to small needle gauge or pulling too hard on syringe, slow draws, excess damage to tissue during venipuncture, excessive mixing, etc.)<br />
<br />
Tests most affected by hemolysis include:<br />
<br />
* Potassium<br />
* ALP<br />
* LDH<br />
* RBC<br />
* Hemoglobin<br />
* Hematocrit<br />
<br />
=== Icterus ===<br />
<br />
=== Lipemia ===<br />
<br />
* Cloudiness of sample due to lipemia affects photometric methods<br />
* May be caused by recent fatty meals or be due to a patient's condition<br />
* Lipemia can be removed by ultracentrifugation of samples<br />
** Do not ultracentrifuge lipid, cholesterol, triglyceride, etc. tests as this removes the fats<br />
<br />
=== Other Factors ===<br />
<br />
* Quantity not sufficient<br />
** Insufficient sample volumes may cause aspiration errors and cause false results<br />
* Diluted specimen<br />
** Dilution of the specimen can be the result of improper collection (e.g., saline or other products from collection above IV lines) or due to adulteration<br />
** These specimens will generally show decreased results due to a dilutional effect<br />
** Serum/plasma may appear very pale, and the ratio of red blood cells to plasma will be off (significantly more plasma than red blood cells)<br />
** Multiple different results may be affected (e.g., chemistry and hematology results, multiple analytes, etc.)<br />
** Certain tests may be affected more depending on the diluting material<br />
*** Contamination from heparinized lines will falsely prolong coagulation results<br />
*Contaminated specimen<br />
**EDTA contamination<br />
***Due to improper collection order (e.g., collection of lavender top EDTA tubes before chemistry tubes)<br />
****Falsely increased potassium (often >10 mmol/L)<br />
****Falsely decreased calcium (often <0.50 mmol/L), magnesium, and alkaline phosphatase (ALP)<br />
*Old or unspun specimens<br />
**The stability of analytes can change as specimens age, especially when red blood cells are not separated from serum/plasma<br />
**Samples should be spun as soon as possible; if a separator gel is not present in the tube, plasma/serum should be aliquoted to a new tube <br />
**Falsely increased potassium (as a major intracellular cation, potassium leaks from red blood cells over time or when cells are damaged)<br />
**Falsely decreased glucose (as glucose is taken up by cells and used for cellular respiration over time as the sample sits)<br />
* Biotin<br />
** Biotin (also known as Vitamin B7, Vitamin H, or coenzyme R) may interfere with biotin-based immunoassays, causing false positive results</div>
Admin
https://medlabwiki.com/index.php?title=Osmometry&diff=236
Osmometry
2026-02-03T03:44:44Z
<p>Admin: </p>
<hr />
<div><br />
Osmometry measures the osmotic strength of the particles within a sample. In clinical labs, this is most commonly performed using freezing point depression methodology.<br />
<br />
=== Methodologies ===<br />
Various techniques can be used to measure osmolality.<br />
{| class="wikitable"<br />
|+<br />
!Technique<br />
!Mechanism<br />
!Strengths<br />
!Limitations<br />
|-<br />
|Freezing Point<br />
|Measures solute by freezing the sample and determining the freezing point.<br />
|<br />
* Accurate<br />
* Can be used to measure volatile solutes<br />
|<br />
|-<br />
|Vapour Pressure<br />
|Measures the decrease in vapour pressure when more solute is present.<br />
|<br />
|Unreliable when measuring volatile compounds (e.g., alcohols, acetone, etc.)<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|}<br />
<br />
<br />
<br />
=== Uses ===<br />
There are a variety of uses for osmometry and made include serum osmolality, urine osmolality, or both.<br />
<br />
* Investigating suspected toxin ingestion:<br />
**Alcohols (ethanol, methanol, isopropanol)<br />
**Ethylene and propylene glycol (antifreeze)<br />
**ASA and other salicylic acids<br />
**Paraldehyde<br />
* Investigation of renal function<br />
* Investigation of diabetes mellitus or diabetes insipidus<br />
*Monitoring osmotically active compounds:<br />
**Mannitol (as treatment for cerebral edema or when used for surgical irrigation)<br />
*Assessment of hyponatremia<br />
**Can differentiate true hyponatremia from pseudohyponatremia<br />
<br />
{| class="wikitable"<br />
! rowspan="2" |Serum Osmolality<br />
! colspan="2" |RI: 275 - 295 mOsm/kg<br />
|-<br />
!▲ Increased<br />
!▼ Decreased<br />
|-<br />
|Conditions<br />
|Toxin ingestion:<br />
<br />
*Alcohols (ethanol, methanol, isopropanol)<br />
*Ethylene and propylene glycol (antifreeze)<br />
*ASA and other salicylic acids<br />
*Paraldehyde<br />
Monitoring osmotically active compounds:<br />
<br />
* Mannitol (as treatment for cerebral edema)<br />
** Therapeutic: osmolar gap ~10 mOsm/kg<br />
** Renal toxicity: osmolar gap ≥50 mOsm/kg<br />
|<br />
|-<br />
|Lab Interferences<br />
|<br />
|<br />
|-<br />
|Other Factors<br />
|<br />
*<br />
|<br />
*<br />
|}</div>
Admin
https://medlabwiki.com/index.php?title=Osmometry&diff=235
Osmometry
2026-02-02T05:32:43Z
<p>Admin: </p>
<hr />
<div><br />
Osmometry measures the osmotic strength of the particles within a sample. In clinical labs, this is most commonly performed using freezing point depression methodology.<br />
<br />
Uses<br />
{| class="wikitable"<br />
! rowspan="2" |Serum Osmolality<br />
! colspan="2" |RI: 275 - 295 mOsm/kg<br />
|-<br />
!▲ Increased<br />
!▼ Decreased<br />
|-<br />
|Conditions<br />
|Toxin ingestion:<br />
<br />
*Ethanol<br />
*<br />
|<br />
|-<br />
|Lab Interferences<br />
|<br />
|<br />
|-<br />
|Other Factors<br />
|<br />
*<br />
|<br />
*<br />
|}</div>
Admin
https://medlabwiki.com/index.php?title=Osmometry&diff=234
Osmometry
2026-01-30T02:03:57Z
<p>Admin: Created page with " Osmometry measures the osmotic strength of the particles within a sample. In clinical labs, this is most commonly performed using freezing point depression methodology. Uses {| class="wikitable" ! rowspan="2" |Serum Osmolality ! colspan="2" |RI: 275 - 295 mOsm/kg |- !▲ Increased !▼ Decreased |- |Conditions |Toxin ingestion: * * | |- |Lab Interferences | | |- |Other Factors | * | * |}"</p>
<hr />
<div><br />
Osmometry measures the osmotic strength of the particles within a sample. In clinical labs, this is most commonly performed using freezing point depression methodology.<br />
<br />
Uses<br />
{| class="wikitable"<br />
! rowspan="2" |Serum Osmolality<br />
! colspan="2" |RI: 275 - 295 mOsm/kg<br />
|-<br />
!▲ Increased<br />
!▼ Decreased<br />
|-<br />
|Conditions<br />
|Toxin ingestion:<br />
<br />
*<br />
*<br />
|<br />
|-<br />
|Lab Interferences<br />
|<br />
|<br />
|-<br />
|Other Factors<br />
|<br />
*<br />
|<br />
*<br />
|}</div>
Admin
https://medlabwiki.com/index.php?title=Blood_Gas_Analysers&diff=233
Blood Gas Analysers
2025-09-23T22:58:08Z
<p>Admin: Created page with "Overview Blood gas analysers are point-of-care devices that provide fast results using whole blood samples. They can generally measure blood gases, hemoglobin and hemoglobin variants, electrolytes, and other important analytes such as glucose or lactic acid"</p>
<hr />
<div>Overview<br />
<br />
Blood gas analysers are point-of-care devices that provide fast results using whole blood samples. They can generally measure blood gases, hemoglobin and hemoglobin variants, electrolytes, and other important analytes such as glucose or lactic acid</div>
Admin
https://medlabwiki.com/index.php?title=Biochemistry&diff=232
Biochemistry
2025-09-23T22:55:46Z
<p>Admin: /* Clinical instrumentation */</p>
<hr />
<div>== General pages ==<br />
Clinical biochemistry involves diagnostic testing of blood and other body fluids for enzymes, proteins, antibodies, and more for the purposes of monitoring and diagnosing disease.<br />
<br />
* [[Chemistry Specimen Processing]]<br />
* [[Chemistry Calculations]]<br />
* [[Interferences]]<br />
<br />
== Clinical instrumentation ==<br />
[[Immunoassays]]<br />
<br />
[[Electrochemical Measurement Systems]] (EMS)<br />
<br />
[[Blood Gas Analysers]] (POCT)<br />
<br />
== Biochemistry by body system ==<br />
[[Cardiac Testing]]<br />
<br />
[[Liver Testing]]<br />
<br />
[[Kidney Testing]]<br />
<br />
== Special topics in biochemistry ==<br />
[[Glucose & Carbohydrates]]<br />
<br />
[[Lipids]]<br />
<br />
[[Enzymes]]<br />
<br />
[[Hormones]]<br />
<br />
[[Electrolytes]]<br />
<br />
[[Osmometry]]<br />
<br />
[[Tumour Markers]]</div>
Admin
https://medlabwiki.com/index.php?title=Electrochemical_Measurement_Systems&diff=231
Electrochemical Measurement Systems
2025-09-21T01:44:49Z
<p>Admin: </p>
<hr />
<div>Types of Electrodes<br />
<br />
* Glass Electrodes<br />
** H+, Na+, K+, Li+, Ag+ NH4+<br />
* pH Combination Electrodes<br />
* Solid State Electrodes<br />
** Cl-<br />
* Liquid Ion-Exchange<br />
** K+ (valinomycin binds K+ in centre ring)<br />
** Ca2+ (organo-phosphate salt in PVC)<br />
* Compound Gas Electrodes<br />
** pCO2 (Severinghaus CO2 electrode)<br />
*** CO2 diffuses past first membrane and alters pH of internal bicarbonate buffer → lowers pH<br />
** pO2 (Clark electrode)<br />
*** o2 reduced at platinum cathode, releasing electrons<br />
* Enzyme Electrodes<br />
** Non-ionic compounds<br />
** Glucose, urea, etc.<br />
** Measure ions generated from enzymatic reactions<br />
<br />
==== Indirect vs Direct Ion-Selective Electrodes (ISEs) ====<br />
{| class="wikitable"<br />
|+<br />
!<br />
!Indirect ISE<br />
!Direct ISE<br />
|-<br />
|Principle<br />
|<br />
* Sample is diluted (generally between 1:16 to 1:34) before the ion concentration is measured<br />
* A fixed volume of sample is diluted, of which the water volume (which contains electrolytes) is assumed to remain constant at 93% of the total volume<br />
* The change in potential is measured, which is converted to a concentration by comparison to a calibration curve<br />
* Measured ion concentration is proportional to the concentration in all phases of plasma<br />
|<br />
* Sample is directly measured without a dilution step<br />
* Measured ion concentration is proportional to the concentration in the water phase<br />
* Results are standardized with indirect ISEs by multiplying result by aqueous portion (93%)<br />
|-<br />
|Benefits<br />
|<br />
* Smaller sample volume is required due to dilution<br />
* Increases electrode lifespan<br />
* Cheaper, suitable for high-volume testing<br />
|<br />
* Whole blood samples can be used<br />
* Unaffected by changes in solid phase of plasma<br />
|-<br />
|Limitations<br />
|<br />
* Subject to electrolyte exclusion effect<br />
** Abnormal levels of solid phase products in plasma (proteins, lipids, etc.) affect results<br />
** Increase in solid phase results in false decrease in measured electrolytes<br />
** Decrease in solid phase results in false increase in measured electrolytes<br />
|<br />
|}<br />
<br />
==== Electrolyte Exclusion Effect ====<br />
<br />
* Blood plasma normally consists of 93% water/aqueous portion (electrolytes, etc.) and 7% solids (includes proteins, lipids, etc.)<br />
* Indirect ISEs have a dilution step, which is based upon the assumption of that of a given volume of plasma, 93% of it will be in the water phase (e.g., for 100 μL of sample, 93 μL will contain electrolytes)<br />
* If there are more solid phase products, then less of the sample will contain electrolytes. However, the sample will be diluted with the same amount of diluent as normal. This results in an over-dilution of the sample, causing falsely low measured ion concentration.<br />
* Conversely, if there are less solid phase products, then more of the sample contains electrolytes. When the sample is diluted with the diluent, there will be a greater volume of aqueous phase electrolytes in the sample than expected for the dilution. This will result in a falsely increased measured ion concentration.<br />
<br />
==== Conditions Associated with the Electrolyte Exclusion Effect ====<br />
Conditions associated with increased plasma solids (and thus falsely decreased electrolyte measurements) include:<br />
<br />
* Hyperlipidemia<br />
** Lipemic samples<br />
* Hyperproteinemia<br />
<br />
'''Pseudohyponatremia''' is caused by erroneous sodium measurements by indirect ISE. It is associated with a low sodium measurement in the presence of normal plasma osmolarity.<br />
<br />
Conditions associated with decrease plasma solids (and thus falsely increased electrolyte measurements) include:</div>
Admin
https://medlabwiki.com/index.php?title=Electrochemical_Measurement_Systems&diff=230
Electrochemical Measurement Systems
2025-09-21T01:01:03Z
<p>Admin: </p>
<hr />
<div>Types of Electrodes<br />
<br />
* Glass Electrodes<br />
** H+, Na+, K+, Li+, Ag+ NH4+<br />
* pH Combination Electrodes<br />
* Solid State Electrodes<br />
** Cl-<br />
* Liquid Ion-Exchange<br />
** K+ (valinomycin binds K+ in centre ring)<br />
** Ca2+ (organo-phosphate salt in PVC)<br />
* Compound Gas Electrodes<br />
** pCO2 (Severinghaus CO2 electrode)<br />
*** CO2 diffuses past first membrane and alters pH of internal bicarbonate buffer → lowers pH<br />
** pO2 (Clark electrode)<br />
*** o2 reduced at platinum cathode, releasing electrons<br />
* Enzyme Electrodes<br />
** Non-ionic compounds<br />
** Glucose, urea, etc.<br />
** Measure ions generated from enzymatic reactions<br />
<br />
Indirect vs Direct Ion-Selective Electrodes (ISEs)<br />
<br />
test2<br />
{| class="wikitable"<br />
|+<br />
!<br />
!Indirect ISE<br />
!Direct ISE<br />
|-<br />
|Principle<br />
|<br />
* Sample is diluted (generally between 1:16 to 1:34) before the ion concentration is measured<br />
|<br />
* Sample is directly measured without a dilution step<br />
|-<br />
|Benefits<br />
|<br />
|<br />
|-<br />
|Limitations<br />
|<br />
|<br />
|}</div>
Admin
https://medlabwiki.com/index.php?title=Electrochemical_Measurement_Systems&diff=229
Electrochemical Measurement Systems
2025-09-21T00:55:39Z
<p>Admin: </p>
<hr />
<div>Types of Electrodes<br />
<br />
* Glass Electrodes<br />
** H+, Na+, K+, Li+, Ag+ NH4+<br />
* pH Combination Electrodes<br />
* Solid State Electrodes<br />
** Cl-<br />
* Liquid Ion-Exchange<br />
** K+ (valinomycin binds K+ in centre ring)<br />
** Ca2+ (organo-phosphate salt in PVC)<br />
* Compound Gas Electrodes<br />
** pCO2 (Severinghaus CO2 electrode)<br />
*** CO2 diffuses past first membrane and alters pH of internal bicarbonate buffer → lowers pH<br />
** pO2 (Clark electrode)<br />
*** o2 reduced at platinum cathode, releasing electrons<br />
* Enzyme Electrodes<br />
** Non-ionic compounds<br />
** Glucose, urea, etc.<br />
** Measure ions generated from enzymatic reactions<br />
<br />
Indirect vs Direct Ion-Selective Electrodes (ISEs)<br />
<br />
test</div>
Admin
https://medlabwiki.com/index.php?title=Interferences&diff=228
Interferences
2025-05-21T00:06:45Z
<p>Admin: </p>
<hr />
<div>There are a variety of different factors that can interfere with laboratory results. The following provides an overview of possible interferences.<br />
<br />
== Specimen Integrity Issues ==<br />
<br />
=== Hemolysis ===<br />
Hemolysis can interfere directly with lab results (due to the release of red blood cell components) or indirectly by affecting <br />
<br />
* May be due to patient's condition (e.g., hemolytic anemia, autoimmune conditions, certain drugs, etc.)<br />
* May be due to improper specimen collection (e.g., too much force during venipuncture due to small needle gauge or pulling too hard on syringe, slow draws, excess damage to tissue during venipuncture, excessive mixing, etc.)<br />
<br />
Tests most affected by hemolysis include:<br />
<br />
* Potassium<br />
* ALP<br />
* LDH<br />
* RBC<br />
* Hemoglobin<br />
* Hematocrit<br />
<br />
=== Icterus ===<br />
<br />
=== Lipemia ===<br />
<br />
* Cloudiness of sample due to lipemia affects photometric methods<br />
* May be caused by recent fatty meals or be due to a patient's condition<br />
* Lipemia can be removed by ultracentrifugation of samples<br />
** Do not ultracentrifuge lipid, cholesterol, triglyceride, etc. tests as this removes the fats<br />
<br />
=== Other Factors ===<br />
<br />
* Quantity not sufficient<br />
** Insufficient sample volumes may cause aspiration errors and cause false results<br />
* Diluted specimen<br />
** Dilution of the specimen can be the result of improper collection (e.g., saline or other products from collection above IV lines) or due to adulteration<br />
** These specimens will generally show decreased results due to a dilutional effect<br />
** Serum/plasma may appear very pale, and the ratio of red blood cells to plasma will be off (significantly more plasma than red blood cells)<br />
** Multiple different results may be affected (e.g., chemistry and hematology results, multiple analytes, etc.)<br />
** Certain tests may be affected more depending on the diluting material<br />
*** Contamination from heparinized lines will falsely prolong coagulation results<br />
*Contaminated specimen<br />
**EDTA contamination may cause falsely decreased calcium and increased potassium<br />
* Biotin<br />
** Biotin (also known as Vitamin B7, Vitamin H, or coenzyme R) may interfere with biotin-based immunoassays, causing false positive results</div>
Admin
https://medlabwiki.com/index.php?title=Interferences&diff=227
Interferences
2025-05-21T00:05:52Z
<p>Admin: Created page with "There are a variety of different factors that can interfere with laboratory results. The following provides an overview of possible interferences. == Specimen Integrity Issues == === Hemolysis === Hemolysis can interfere directly with lab results (due to the release of red blood cell components) or indirectly by affecting * May be due to patient's condition (e.g., hemolytic anemia, autoimmune conditions, certain drugs, etc.) * May be due to improper specimen collecti..."</p>
<hr />
<div>There are a variety of different factors that can interfere with laboratory results. The following provides an overview of possible interferences.<br />
<br />
== Specimen Integrity Issues ==<br />
<br />
=== Hemolysis ===<br />
Hemolysis can interfere directly with lab results (due to the release of red blood cell components) or indirectly by affecting <br />
<br />
* May be due to patient's condition (e.g., hemolytic anemia, autoimmune conditions, certain drugs, etc.)<br />
* May be due to improper specimen collection (e.g., too much force during venipuncture due to small needle gauge or pulling too hard on syringe, slow draws, excess damage to tissue during venipuncture, excessive mixing, etc.)<br />
<br />
Tests most affected by hemolysis include:<br />
<br />
* Potassium<br />
* ALP<br />
* LDH<br />
* RBC<br />
* Hemoglobin<br />
* Hematocrit<br />
<br />
=== Icterus ===<br />
<br />
=== Lipemia ===<br />
<br />
* Cloudiness of sample due to lipemia affects photometric methods<br />
* May be caused by recent fatty meals or be due to a patient's condition<br />
* Lipemia can be removed by ultracentrifugation of samples<br />
** Do not ultracentrifuge lipid, cholesterol, triglyceride, etc. tests as this removes the fats<br />
<br />
=== Other Factors ===<br />
<br />
* Quantity not sufficient<br />
** Insufficient sample volumes may cause aspiration errors and cause false results<br />
* Diluted specimen<br />
** Dilution of the specimen can be the result of improper collection (e.g., saline or other products from collection above IV lines) or due to adulteration<br />
** These specimens will generally show decreased results due to a dilutional effect<br />
** Serum/plasma may appear very pale, and the ratio of red blood cells to plasma will be off (significantly more plasma than red blood cells)<br />
** Multiple different results may be affected (e.g., chemistry and hematology results, multiple analytes, etc.)<br />
** Certain tests may be affected more depending on the diluting material<br />
*** Contamination from heparinized lines will falsely prolong coagulation results<br />
* Biotin<br />
** Biotin (also known as Vitamin B7, Vitamin H, or coenzyme R) may interfere with biotin-based immunoassays, causing false positive results</div>
Admin
https://medlabwiki.com/index.php?title=Biochemistry&diff=226
Biochemistry
2025-05-20T23:51:17Z
<p>Admin: </p>
<hr />
<div>== General pages ==<br />
Clinical biochemistry involves diagnostic testing of blood and other body fluids for enzymes, proteins, antibodies, and more for the purposes of monitoring and diagnosing disease.<br />
<br />
* [[Chemistry Specimen Processing]]<br />
* [[Chemistry Calculations]]<br />
* [[Interferences]]<br />
<br />
== Clinical instrumentation ==<br />
[[Immunoassays]]<br />
<br />
[[Electrochemical Measurement Systems]] (EMS)<br />
<br />
== Biochemistry by body system ==<br />
[[Cardiac Testing]]<br />
<br />
[[Liver Testing]]<br />
<br />
[[Kidney Testing]]<br />
<br />
== Special topics in biochemistry ==<br />
[[Glucose & Carbohydrates]]<br />
<br />
[[Lipids]]<br />
<br />
[[Enzymes]]<br />
<br />
[[Hormones]]<br />
<br />
[[Electrolytes]]<br />
<br />
[[Osmometry]]<br />
<br />
[[Tumour Markers]]</div>
Admin
https://medlabwiki.com/index.php?title=Chemistry_Specimen_Processing&diff=225
Chemistry Specimen Processing
2025-05-18T16:15:57Z
<p>Admin: /* Lab Test Reference Intervals */</p>
<hr />
<div>Separate serum/plasma from blood cells within 2 hours<br />
<br />
* For serum, need to wait for specimen to clot first (20-30 min)<br />
Store samples at 4C when not being run<br />
<br />
For longer-term storage, store at minimum -20C<br />
{| class="wikitable"<br />
|+<br />
!Analyte<br />
!Specimen Type<br />
!Collection Media<br />
!Collection Notes<br />
!Reference Interval<br />
|-<br />
|Sodium<br />
|<br />
|Lithium heparin<br />
|<br />
|135 - 145 mmol/L<br />
|-<br />
|Potassium<br />
|<br />
|Lithium heparin<br />
|<br />
|3.5-5.0 mmol/L<br />
|-<br />
| rowspan="2" |Glucose<br />
|Fasting<br />
|<br />
|<br />
|4.1 - 5.6 mmol/L<br />
|-<br />
|Random<br />
|<br />
|<br />
|<br />
|-<br />
| rowspan="2" |Creatinine<br />
|Urine, 24 hour<br />
|<br />
|<br />
|<br />
|-<br />
|Blood serum<br />
|Lithium heparin<br />
|<br />
|<br />
|-<br />
|Serum Iron<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Ferritin<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Total Iron Binding Capacity<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|% Transferrin Saturation<br />
|<br />
|<br />
|<br />
|20-55%<br />
|-<br />
| rowspan="3" |Urea<br />
|Blood serum or plasma<br />
|Lithium heparin<br />
|<br />
|2.1 - 7.1 mmol/L<br />
|-<br />
|Urine, random<br />
|<br />
|Use thymol preservative and refrigerate<br />
|<br />
|-<br />
|Urine, 24 hour<br />
|<br />
|Use thymol preservative and refrigerate<br />
|430 - 710 mmol/day<br />
|-<br />
| rowspan="2" |Uric Acid<br />
|Blood serum or plasma<br />
|Lithium heparin<br />
|<br />
|<br />
|-<br />
|Urine, 24 hour<br />
|<br />
|<br />
|<br />
|-<br />
|Urinalysis<br />
|Urine, first morning midstream clean-catch preferred<br />
|<br />
|Fresh samples <2h old<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|}<br />
Special Samples:<br />
<br />
* Keep on ice<br />
** Blood gases<br />
** Ammonia<br />
* Protect from light<br />
** Bilirubin<br />
** Vitamin B12<br />
<br />
== Lab Test Reference Intervals ==<br />
{| class="wikitable"<br />
|+<br />
!Test<br />
!Reference Interval<br />
!↑ Conditions<br />
!↓ Conditions<br />
!Interferences<br />
!Notes<br />
|-<br />
|Sodium<br />
|135 - 145 mmol/L<br />
|Hypernatremia<br />
|<br />
|<br />
|<br />
|-<br />
|Potassium<br />
|3.5 - 5.0 mmol/L<br />
|<br />
|<br />
|<br />
* ↑↑↑ Hemolysis<br />
|<br />
|-<br />
|Chloride<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Bicarbonate<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Anion Gap<br />
|10 - 20 mmol/L<br />
|<br />
* Ketoacidosis (diabetes, starvation)<br />
* Renal failure<br />
* Lactic acidosis<br />
* Hypernatremia<br />
* Poisoning (methanol, ethanol, ethylene glycol, salicylates)<br />
|Rare<br />
<br />
* Hypoalbuminemia<br />
* Severe hypercalcemia<br />
|<br />
|<br />
|-<br />
|pH<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|pO<sub>2</sub><br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|pCO<sub>2</sub><br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|[HCO<sub>3</sub><sup>-</sup>]<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Glucose, fasting<br />
|4.1 - 5.6 mmol/L<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Glucose, random<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Total Bilirubin<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Unconjugated Bilirubin<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Conjugated Bilirubin<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|eGFR<br />
|>2.0 mL/s<br />
|<br />
|<br />
|<br />
|Preferred over creatinine clearance<br />
|-<br />
|Urine flow rate<br />
|0.05 mL/s<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Creatinine (serum)<br />
|62 - 115 μmol/L (male)<br />
53 - 97 μmol/L (female)<br />
|<br />
|<br />
| rowspan="3" |<br />
* ↑ Hemolysis<br />
* ↓ Icterus<br />
* ↓ Lipemia<br />
* Ammonium heparin<br />
* Non-specific chromogens<br />
|<br />
|-<br />
|Creatinine (urine, 24h)<br />
|9 - 18 mmol/d (male)<br />
7 - 16 mmol/d (female)<br />
|<br />
|<br />
|Inaccuracies may arise from improper urine measurement or tubular secretion.<br />
|-<br />
|Creatinine Clearance<br />
|1.42 - 2.08 mL/s (male)<br />
1.24 - 1.92 mL/s (female)<br />
|<br />
|<br />
|<0.63 mL/s is markedly decreased<br />
High serum creatinine may over-estimate CC.<br />
|-<br />
|[[Cardiac Testing#C-reactive protein|C-reactive protein]]<br />
|<10 mg/L<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|}<br />
Blood Gas Results<br />
{| class="wikitable"<br />
!Test<br />
!Reference Interval<br />
!Clinical Relevance<br />
!Notes<br />
|-<br />
|Sodium<br />
|135 - 145 mmol/L<br />
|<br />
|<br />
|-<br />
|Potassium<br />
|3.5 - 5.0 mmol/L<br />
|<br />
|<br />
|-<br />
|Chloride<br />
|<br />
|<br />
|<br />
|-<br />
|pH<br />
|7.35 - 7.45<br />
|<br />
|<br />
|-<br />
|pO<sub>2</sub><br />
|<br />
|<br />
|<br />
|-<br />
|pCO<sub>2</sub><br />
|35 - 45 mmHg<br />
|<br />
|<br />
|-<br />
|[HCO<sub>3</sub><sup>-</sup>]<br />
|21 - 28 mmol/L<br />
|<br />
|<br />
|}<br />
Heme -> bilirubin -> unconjugated bilirubin (transport via albumin) -> conjugated bili -> urobilinogen (in GI) -> urobilin excreted<br />
<br />
Hepatic Jaundice<br />
<br />
* ↑ AST, ALT, GGT <br />
* ALP N/↑<br />
* ↑ Total, unconj., conj. bilirubin<br />
<br />
Obstructive (post-hepatic) jaundice<br />
<br />
* ↑↑ ALP and GGT<br />
* ↑ Bilirubin<br />
* ALT, AST vary<br />
<br />
Enzymes<br />
<br />
* ALT most liver specific<br />
** Except alcoholic cirrhosis AST 2x ALT<br />
* AST more general (liver, skeletal muscle, heart, RBCs)<br />
* GGT sensitive to liver injury, but not specific (high in alcoholic liver cirrhosis)<br />
* LD not specific<br />
* ALP non-specific<br />
* ↓ albumin, ↑ gamma globulins (IgG, IgM hepatitis; IgA alcoholic cirrhosis)<br />
** Beta-gamma bridging<br />
<br />
Pancreatitis<br />
<br />
* Amylase<br />
* Lipase (more specific than amylase)<br />
<br />
Affected by HIL<br />
<br />
* K<sup>+</sup><br />
* LD very sensitive!!! and unstable!!!<br />
* AST<br />
* Bilirubin<br />
** ↓ Hemolysis<br />
** ↑ Lipemia<br />
<br />
Less Affected<br />
<br />
* Na (dilutional effect)<br />
* Cl (dilutional effect)<br />
* ALP<br />
* CK (gross hemolysis false ↑)<br />
<br />
CSF Tubes<br />
<br />
# Chemistry<br />
# Microbiology<br />
# Hematology<br />
# Other (e.g., cytology)<br />
<br />
Hashimoto = low T3,T4 and high TSH<br />
<br />
Grave's = hyperthyroidism = excess T4, low TSH<br />
<br />
Cushing's = high cortisol =<br />
<br />
* High ACTH with ACTH-dependent (pituitary)<br />
* Low ACTH with independent (adrenal cancer, etc.)<br />
* Higher part of the body is high ACTH and dependent (pituitary); lower part of the body is low ACTH and independent (adrenal)<br />
<br />
Cardiac Markers<br />
<br />
* Myoglobin = earliest marker (but declines quickly)<br />
* CK elevated in cardiac and skeletal disorders<br />
** CK-MB/CK2 most specific isoenzyme for cardiac issues (but also skeletal)<br />
* Cardiac troponin 1 is very cardiac-specific!<br />
** High sensitivity cTnI used for investigating heart attacks<br />
** Detectable quickly (3-12 hours), and remain elevated >1 week<br />
* NT-proBNP elevated in heart failure<br />
* CRP acute marker of inflammation, can help evaluate risk for CVD</div>
Admin
https://medlabwiki.com/index.php?title=Liver_Testing&diff=224
Liver Testing
2025-05-12T03:17:32Z
<p>Admin: </p>
<hr />
<div>The following markers are commonly used to evaluate liver function and assess disease.<br />
<br />
* Alkaline phosphotase (ALP)<br />
* Alanine transaminase (ALT)<br />
* Aspartate amino transferase (AST)<br />
* Gamma-glutamyl transferase (GGT)<br />
* Lactate dehydrogenase (LDH)<br />
* Bilirubin<br />
* Albumin<br />
* Total protein<br />
<br />
Additionally, hematology tests may provide some indication of disease states, including:<br />
<br />
* Peripheral blood film<br />
* Coagulation testing<br />
<br />
Other testing may be performed for specific liver-related diseases.<br />
<br />
* Hepatitis B<br />
**<br />
* Hepatitis C<br />
** anti-HCV antibody testing<br />
** HCV RNA nucleic acid testing (quantitative or qualitative)<br />
<br />
== Overview ==<br />
Elevated liver markers can indicate liver disorders or be due to other causes as they are often non-specific<br />
<br />
* AST may be increased due to liver disease, or due to damage to cardiac or skeletal muscle<br />
** Associated with liver disorders including hepatitis<br />
** Moderately increased in alcoholic cirrhosis - tends to be 2x that of ALT<br />
* '''ALT is found mainly in liver''', but also in heart and skeletal muscle<br />
** Often increased with liver diseases<br />
** Highest in viral hepatitis<br />
* GGT is found in liver, along with other areas like the kidney, brain, prostate, and pancreas<br />
** '''Most sensitive for liver disease''', but not very specific!<br />
** Associated with bile duct obstruction and chronic alcoholism<br />
* ALP non-specific<br />
* LDH consists of 5 isoenzymes, and is not specific<br />
<br />
Hepatitis C<br />
<br />
* anti-HCV antibody testing detects current or past infection (detectable at 8-11 weeks)<br />
* HCV RNA testing detects current infection (detectable at 1-2 weeks)</div>
Admin
https://medlabwiki.com/index.php?title=Liver_Testing&diff=223
Liver Testing
2025-05-11T03:54:12Z
<p>Admin: Created page with "The following markers are commonly used to evaluate liver function and assess disease. * ALP * ALT * AST * GGT * LDH * Bilirubin * Albumin * Total protein Additionally, hematology tests may provide some indication of disease states, including: * Peripheral blood film * Coagulation testing Other testing may be performed for specific liver-related diseases. * Hepatitis B ** * Hepatitis C"</p>
<hr />
<div>The following markers are commonly used to evaluate liver function and assess disease.<br />
<br />
* ALP<br />
* ALT<br />
* AST<br />
* GGT<br />
* LDH<br />
* Bilirubin<br />
* Albumin<br />
* Total protein<br />
<br />
Additionally, hematology tests may provide some indication of disease states, including:<br />
<br />
* Peripheral blood film<br />
* Coagulation testing<br />
<br />
Other testing may be performed for specific liver-related diseases.<br />
<br />
* Hepatitis B<br />
**<br />
* Hepatitis C</div>
Admin
https://medlabwiki.com/index.php?title=Cardiac_Testing&diff=222
Cardiac Testing
2025-03-03T04:41:34Z
<p>Admin: </p>
<hr />
<div>Cardiac testing in the lab generally involves monitoring of cardiac markers, which are elevated when damage occurs to the heart. These markers include:<br />
<br />
* C-reactive protein (CRP)<br />
* Creatine kinase (CK)<br />
* Myoglobin<br />
* NT-proBNP<br />
* Troponins<br />
<br />
== Overview ==<br />
<br />
* '''Myoglobin is earliest marker''' (but declines quickly)<br />
* '''Cardiac troponin 1 is most cardiac-specific'''<br />
** High-sensitivity cTnI used for investigating heart attacks<br />
** Detectable quickly (3-12 hours), and remain elevated >1 week<br />
* '''CK-MB/CK2 occurs later and lasts longer''' (CK isoenzyme associated with cardiac and skeletal muscle)<br />
<br />
Others<br />
<br />
* CRP is acute inflammatory marker, can also be used to assess future risk for CVD<br />
* NT-proBNP elevated in heart failure<br />
<br />
== C-reactive protein ==<br />
C-reactive protein is an non-specific, acute phase reactant that is produced as a part of inflammatory processes. The assay can be used to investigate a variety of disorders that are associated with inflammation, including infections, autoimmune conditions, necrosis, etc.<br />
<br />
* CRP is generally a better indicator of inflammatory processes than the ESR.<br />
<br />
{| class="wikitable"<br />
|+<br />
! rowspan="2" |C-reactive protein<br />
! colspan="2" |RI: <10 mg/L<br />
|-<br />
!▲ Increased<br />
!▼ Decreased<br />
|-<br />
|Conditions<br />
|<br />
* Bacterial infections<br />
* Surgical complications (e.g., infection, clots)<br />
* Autoimmune diseases (arthritis, Crohn's disease, etc.)<br />
* Vascular diseases<br />
** Including increased risk of cardiovascular ischemia<br />
* Tissue damage<br />
** Acute myocardial infarction<br />
* Malignancy<br />
|<br />
|-<br />
|Lab Interferences<br />
|<br />
|<br />
|-<br />
|Other Factors<br />
|<br />
* Smoking<br />
* Hypertension<br />
* Low HDL/high triglycerides<br />
* Elevated BMI<br />
* Diabetes<br />
* Chronic infections (e.g., gingivitis)<br />
* Medications<br />
|<br />
* Medications, especially anti-inflammatory drugs<br />
* Exercise, weight loss<br />
* Alcohol consumption<br />
|}<br />
<br />
== High-sensitivity C-reactive protein ==<br />
This CRP assay has an increased sensitivity, allowing for the monitoring of low-level inflammation that may indicate future cardiac events.<br />
<br />
* Athermomatous plaques in arteries release inflammatory molecules, making baseline hs-CRP values useful in monitoring risk of future cardiac events in patients with stable or acute coronary diseases.<br />
** Low risk: 0.7 - 1.1 mg/L<br />
** Moderate risk: 1.2 - 1.9 mg/L<br />
** High risk: 2.0 - 3.8 mg/L<br />
* Can be used alongside lipid testing for cardiac risk scores (e.g., Framingham risk score)<br />
<br />
== Creatine kinase ==<br />
This non-specific enzyme is has 3 isoenzymes that are found within various tissues, including the heart, skeletal muscle, and brain.<br />
<br />
* CK-MM (96-100%)<br />
* '''CK-MB (CK2) (0-6%)'''<br />
* CK-BB (0%)<br />
<br />
CK-MB is the enzyme that is most specific for heart muscle damage.<br />
<br />
* Levels rise 3-6 hours after damage<br />
* After damage stops, peaks 12-24 hours after<br />
* Returns to normal 12-48 hours after peak (4-5 days total)<br />
<br />
{| class="wikitable"<br />
! rowspan="2" |Creatine Kinase<br />
!<br />
* Adult Male: 20 - 215 IU/L<br />
* Adult Female: 20 - 160 IU/L<br />
* Newborn: 68 - 580 IU/L<br />
|-<br />
!▲ Increased<br />
|-<br />
|Conditions<br />
|<br />
* Acute myocardial infarction<br />
* Cardiac surgeries<br />
* Cardiac defibrillation<br />
* Myocarditis<br />
* Ventricular arrhythmias<br />
* Cardiac ischemia<br />
|-<br />
|Lab Interferences<br />
|<br />
|-<br />
|Other Factors<br />
|<br />
* Damage to skeletal muscle can also increase CK<br />
* Intramuscular injections can increase CK levels<br />
|}<br />
[[Category:Chemistry]]</div>
Admin
https://medlabwiki.com/index.php?title=Cardiac_Testing&diff=221
Cardiac Testing
2025-03-03T04:40:58Z
<p>Admin: </p>
<hr />
<div>Cardiac testing in the lab generally involves monitoring of cardiac markers, which are elevated when damage occurs to the heart. These markers include:<br />
<br />
* C-reactive protein (CRP)<br />
* Creatine kinase (CK)<br />
* Myoglobin<br />
* NT-proBNP<br />
* Troponins<br />
<br />
== Overview ==<br />
<br />
* '''Myoglobin is earliest marker''' (but declines quickly)<br />
* '''Cardiac troponin 1 is most cardiac-specific'''<br />
** High-sensitivity cTnI used for investigating heart attacks<br />
** Detectable quickly (3-12 hours), and remain elevated >1 week<br />
* '''CK-MB/CK2 occurs later and lasts longer''' (CK isoenzyme associated with cardiac and skeletal muscle)<br />
<br />
Others<br />
<br />
* CRP is acute inflammatory marker, can also be used to assess future risk for CVD<br />
* NT-proBNP elevated in heart failure<br />
<br />
== C-reactive protein ==<br />
C-reactive protein is an non-specific, acute phase reactant that is produced as a part of inflammatory processes. The assay can be used to investigate a variety of disorders that are associated with inflammation, including infections, autoimmune conditions, necrosis, etc.<br />
<br />
* CRP is generally a better indicator of inflammatory processes than the ESR.<br />
<br />
{| class="wikitable"<br />
|+<br />
! rowspan="2" |C-reactive protein<br />
! colspan="2" |RI: <10 mg/L<br />
|-<br />
!▲ Increased<br />
!▼ Decreased<br />
|-<br />
|Conditions<br />
|<br />
* Bacterial infections<br />
* Surgical complications (e.g., infection, clots)<br />
* Autoimmune diseases (arthritis, Crohn's disease, etc.)<br />
* Vascular diseases<br />
** Including increased risk of cardiovascular ischemia<br />
* Tissue damage<br />
** Acute myocardial infarction<br />
* Malignancy<br />
|<br />
|-<br />
|Lab Interferences<br />
|<br />
|<br />
|-<br />
|Other Factors<br />
|<br />
* Smoking<br />
* Hypertension<br />
* Low HDL/high triglycerides<br />
* Elevated BMI<br />
* Diabetes<br />
* Chronic infections (e.g., gingivitis)<br />
* Medications<br />
|<br />
* Medications, especially anti-inflammatory drugs<br />
* Exercise, weight loss<br />
* Alcohol consumption<br />
|}<br />
<br />
== High-sensitivity C-reactive protein ==<br />
This CRP assay has an increased sensitivity, allowing for the monitoring of low-level inflammation that may indicate future cardiac events.<br />
<br />
* Athermomatous plaques in arteries release inflammatory molecules, making baseline hs-CRP values useful in monitoring risk of future cardiac events in patients with stable or acute coronary diseases.<br />
** Low risk: 0.7 - 1.1 mg/L<br />
** Moderate risk: 1.2 - 1.9 mg/L<br />
** High risk: 2.0 - 3.8 mg/L<br />
* Can be used alongside lipid testing for cardiac risk scores (e.g., Framingham risk score)<br />
<br />
== Creatine kinase ==<br />
This non-specific enzyme is has 3 isoenzymes that are found within various tissues, including the heart, skeletal muscle, and brain.<br />
<br />
* CK-MM (96-100%)<br />
* '''CK-MB (CK2) (0-6%)'''<br />
* CK-BB (0%)<br />
<br />
CK-MB is the enzyme that is most specific for heart muscle damage.<br />
<br />
* Levels rise 3-6 hours after damage<br />
* After damage stops, peaks 12-24 hours after<br />
* Returns to normal 12-48 hours after peak (4-5 days total)<br />
<br />
{| class="wikitable"<br />
! rowspan="2" |Creatine Kinase<br />
!Adult Male: 20 - 215 IU/L<br />
Adult Female: 20 - 160 IU/L<br />
Newborn: 68 - 580 IU/L<br />
|-<br />
!▲ Increased<br />
|-<br />
|Conditions<br />
|<br />
* Acute myocardial infarction<br />
* Cardiac surgeries<br />
* Cardiac defibrillation<br />
* Myocarditis<br />
* Ventricular arrhythmias<br />
* Cardiac ischemia<br />
|-<br />
|Lab Interferences<br />
|<br />
|-<br />
|Other Factors<br />
|<br />
* Damage to skeletal muscle can also increase CK<br />
* Intramuscular injections can increase CK levels<br />
|}<br />
[[Category:Chemistry]]</div>
Admin
https://medlabwiki.com/index.php?title=Chemistry_Specimen_Processing&diff=220
Chemistry Specimen Processing
2025-03-03T03:41:09Z
<p>Admin: /* Lab Test Reference Intervals */</p>
<hr />
<div>Separate serum/plasma from blood cells within 2 hours<br />
<br />
* For serum, need to wait for specimen to clot first (20-30 min)<br />
Store samples at 4C when not being run<br />
<br />
For longer-term storage, store at minimum -20C<br />
{| class="wikitable"<br />
|+<br />
!Analyte<br />
!Specimen Type<br />
!Collection Media<br />
!Collection Notes<br />
!Reference Interval<br />
|-<br />
|Sodium<br />
|<br />
|Lithium heparin<br />
|<br />
|135 - 145 mmol/L<br />
|-<br />
|Potassium<br />
|<br />
|Lithium heparin<br />
|<br />
|3.5-5.0 mmol/L<br />
|-<br />
| rowspan="2" |Glucose<br />
|Fasting<br />
|<br />
|<br />
|4.1 - 5.6 mmol/L<br />
|-<br />
|Random<br />
|<br />
|<br />
|<br />
|-<br />
| rowspan="2" |Creatinine<br />
|Urine, 24 hour<br />
|<br />
|<br />
|<br />
|-<br />
|Blood serum<br />
|Lithium heparin<br />
|<br />
|<br />
|-<br />
|Serum Iron<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Ferritin<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Total Iron Binding Capacity<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|% Transferrin Saturation<br />
|<br />
|<br />
|<br />
|20-55%<br />
|-<br />
| rowspan="3" |Urea<br />
|Blood serum or plasma<br />
|Lithium heparin<br />
|<br />
|2.1 - 7.1 mmol/L<br />
|-<br />
|Urine, random<br />
|<br />
|Use thymol preservative and refrigerate<br />
|<br />
|-<br />
|Urine, 24 hour<br />
|<br />
|Use thymol preservative and refrigerate<br />
|430 - 710 mmol/day<br />
|-<br />
| rowspan="2" |Uric Acid<br />
|Blood serum or plasma<br />
|Lithium heparin<br />
|<br />
|<br />
|-<br />
|Urine, 24 hour<br />
|<br />
|<br />
|<br />
|-<br />
|Urinalysis<br />
|Urine, first morning midstream clean-catch preferred<br />
|<br />
|Fresh samples <2h old<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|}<br />
Special Samples:<br />
<br />
* Keep on ice<br />
** Blood gases<br />
** Ammonia<br />
* Protect from light<br />
** Bilirubin<br />
** Vitamin B12<br />
<br />
== Lab Test Reference Intervals ==<br />
{| class="wikitable"<br />
|+<br />
!Test<br />
!Reference Interval<br />
!Clinical Relevance<br />
!Interferences<br />
!Notes<br />
|-<br />
|Sodium<br />
|135 - 145 mmol/L<br />
|<br />
|<br />
|<br />
|-<br />
|Potassium<br />
|3.5 - 5.0 mmol/L<br />
|<br />
|<br />
|<br />
|-<br />
|Chloride<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|pH<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|pO<sub>2</sub><br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|pCO<sub>2</sub><br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|[HCO<sub>3</sub><sup>-</sup>]<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Glucose, fasting<br />
|4.1 - 5.6 mmol/L<br />
|<br />
|<br />
|<br />
|-<br />
|Glucose, random<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Total Bilirubin<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Unconjugated Bilirubin<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Conjugated Bilirubin<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|eGFR<br />
|>2.0 mL/s<br />
|<br />
|<br />
|Preferred over creatinine clearance<br />
|-<br />
|Urine flow rate<br />
|0.05 mL/s<br />
|<br />
|<br />
|<br />
|-<br />
|Creatinine (serum)<br />
|62 - 115 μmol/L (male)<br />
53 - 97 μmol/L (female)<br />
|<br />
| rowspan="3" |<br />
* ↑ Hemolysis<br />
* ↓ Icterus<br />
* ↓ Lipemia<br />
* Ammonium heparin<br />
* Non-specific chromogens<br />
|<br />
|-<br />
|Creatinine (urine, 24h)<br />
|9 - 18 mmol/d (male)<br />
7 - 16 mmol/d (female)<br />
|<br />
|Inaccuracies may arise from improper urine measurement or tubular secretion.<br />
|-<br />
|Creatinine Clearance<br />
|1.42 - 2.08 mL/s (male)<br />
1.24 - 1.92 mL/s (female)<br />
|<br />
|<0.63 mL/s is markedly decreased<br />
High serum creatinine may over-estimate CC.<br />
|-<br />
|[[Cardiac Testing#C-reactive protein|C-reactive protein]]<br />
|<10 mg/L<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|}<br />
Blood Gas Results<br />
{| class="wikitable"<br />
!Test<br />
!Reference Interval<br />
!Clinical Relevance<br />
!Notes<br />
|-<br />
|Sodium<br />
|135 - 145 mmol/L<br />
|<br />
|<br />
|-<br />
|Potassium<br />
|3.5 - 5.0 mmol/L<br />
|<br />
|<br />
|-<br />
|Chloride<br />
|<br />
|<br />
|<br />
|-<br />
|pH<br />
|7.35 - 7.45<br />
|<br />
|<br />
|-<br />
|pO<sub>2</sub><br />
|<br />
|<br />
|<br />
|-<br />
|pCO<sub>2</sub><br />
|35 - 45 mmHg<br />
|<br />
|<br />
|-<br />
|[HCO<sub>3</sub><sup>-</sup>]<br />
|21 - 28 mmol/L<br />
|<br />
|<br />
|}<br />
Heme -> bilirubin -> unconjugated bilirubin (transport via albumin) -> conjugated bili -> urobilinogen (in GI) -> urobilin excreted<br />
<br />
Hepatic Jaundice<br />
<br />
* ↑ AST, ALT, GGT <br />
* ALP N/↑<br />
* ↑ Total, unconj., conj. bilirubin<br />
<br />
Obstructive (post-hepatic) jaundice<br />
<br />
* ↑↑ ALP and GGT<br />
* ↑ Bilirubin<br />
* ALT, AST vary<br />
<br />
Enzymes<br />
<br />
* ALT most liver specific<br />
** Except alcoholic cirrhosis AST 2x ALT<br />
* AST more general (liver, skeletal muscle, heart, RBCs)<br />
* GGT sensitive to liver injury, but not specific (high in alcoholic liver cirrhosis)<br />
* LD not specific<br />
* ALP non-specific<br />
* ↓ albumin, ↑ gamma globulins (IgG, IgM hepatitis; IgA alcoholic cirrhosis)<br />
** Beta-gamma bridging<br />
<br />
Pancreatitis<br />
<br />
* Amylase<br />
* Lipase (more specific than amylase)<br />
<br />
Affected by HIL<br />
<br />
* K<sup>+</sup><br />
* LD very sensitive!!! and unstable!!!<br />
* AST<br />
* Bilirubin<br />
** ↓ Hemolysis<br />
** ↑ Lipemia<br />
<br />
Less Affected<br />
<br />
* Na (dilutional effect)<br />
* Cl (dilutional effect)<br />
* ALP<br />
* CK (gross hemolysis false ↑)<br />
<br />
CSF Tubes<br />
<br />
# Chemistry<br />
# Microbiology<br />
# Hematology<br />
# Other (e.g., cytology)<br />
<br />
Hashimoto = low T3,T4 and high TSH<br />
<br />
Grave's = hyperthyroidism = excess T4, low TSH<br />
<br />
Cushing's = high cortisol =<br />
<br />
* High ACTH with ACTH-dependent (pituitary)<br />
* Low ACTH with independent (adrenal cancer, etc.)<br />
* Higher part of the body is high ACTH and dependent (pituitary); lower part of the body is low ACTH and independent (adrenal)<br />
<br />
Cardiac Markers<br />
<br />
* Myoglobin = earliest marker (but declines quickly)<br />
* CK elevated in cardiac and skeletal disorders<br />
** CK-MB/CK2 most specific isoenzyme for cardiac issues (but also skeletal)<br />
* Cardiac troponin 1 is very cardiac-specific!<br />
** High sensitivity cTnI used for investigating heart attacks<br />
** Detectable quickly (3-12 hours), and remain elevated >1 week<br />
* NT-proBNP elevated in heart failure<br />
* CRP acute marker of inflammation, can help evaluate risk for CVD</div>
Admin
https://medlabwiki.com/index.php?title=Cardiac_Testing&diff=219
Cardiac Testing
2025-03-03T00:15:34Z
<p>Admin: </p>
<hr />
<div>Cardiac testing in the lab generally involves monitoring of cardiac markers, which are elevated when damage occurs to the heart. These markers include:<br />
<br />
* C-reactive protein (CRP)<br />
* Creatinine kinase (CK)<br />
* Myoglobin<br />
* NT-proBNP<br />
* Troponins<br />
<br />
== Overview ==<br />
<br />
* '''Myoglobin is earliest marker''' (but declines quickly)<br />
* '''Cardiac troponin 1 is most cardiac-specific'''<br />
** High-sensitivity cTnI used for investigating heart attacks<br />
** Detectable quickly (3-12 hours), and remain elevated >1 week<br />
* '''CK-MB/CK2 occurs later and lasts longer''' is (isoenzyme associated with cardiac and skeletal muscle)<br />
<br />
Others<br />
<br />
* CRP is acute inflammatory marker, can also be used to assess future risk for CVD<br />
* NT-proBNP elevated in heart failure<br />
<br />
== C-reactive protein ==<br />
C-reactive protein is an non-specific, acute phase reactant that is produced as a part of inflammatory processes. The assay can be used to investigate a variety of disorders that are associated with inflammation, including infections, autoimmune conditions, necrosis, etc.<br />
<br />
* CRP is generally a better indicator of inflammatory processes than the ESR.<br />
<br />
{| class="wikitable"<br />
|+<br />
! rowspan="2" |C-reactive protein<br />
! colspan="2" |RI: <10 mg/L<br />
|-<br />
!▲ Increased<br />
!▼ Decreased<br />
|-<br />
|Conditions<br />
|<br />
* Bacterial infections<br />
* Surgical complications (e.g., infection, clots)<br />
* Autoimmune diseases (arthritis, Crohn's disease, etc.)<br />
* Vascular diseases<br />
** Including increased risk of cardiovascular ischemia<br />
* Tissue damage<br />
** Acute myocardial infarction<br />
* Malignancy<br />
|<br />
|-<br />
|Lab Interferences<br />
|<br />
|<br />
|-<br />
|Other Factors<br />
|<br />
* Smoking<br />
* Hypertension<br />
* Low HDL/high triglycerides<br />
* Elevated BMI<br />
* Diabetes<br />
* Chronic infections (e.g., gingivitis)<br />
* Medications<br />
|<br />
* Medications, especially anti-inflammatory drugs<br />
* Exercise, weight loss<br />
* Alcohol consumption<br />
|}<br />
<br />
== High-sensitivity C-reactive protein ==<br />
This CRP assay has an increased sensitivity, allowing for the monitoring of low-level inflammation that may indicate future cardiac events.<br />
<br />
* Athermomatous plaques in arteries release inflammatory molecules, making baseline hs-CRP values useful in monitoring risk of future cardiac events in patients with stable or acute coronary diseases.<br />
** Low risk: 0.7 - 1.1 mg/L<br />
** Moderate risk: 1.2 - 1.9 mg/L<br />
** High risk: 2.0 - 3.8 mg/L<br />
* Can be used alongside lipid testing for cardiac risk scores (e.g., Framingham risk score)<br />
<br />
== Creatinine kinase ==<br />
This non-specific enzyme is has 3 isoenzymes that are found within various tissues, including the heart, skeletal muscle, and brain.<br />
<br />
* CK-MM (96-100%)<br />
* '''CK-MB (CK2) (0-6%)'''<br />
* CK-BB (0%)<br />
<br />
CK-MB is the enzyme that is most specific for heart muscle damage.<br />
<br />
* Levels rise 3-6 hours after damage<br />
* After damage stops, peaks 12-24 hours after<br />
* Returns to normal 12-48 hours after peak (4-5 days total)<br />
<br />
{| class="wikitable"<br />
! rowspan="2" |Creatinine Kinase<br />
!Adult Male: 20 - 215 IU/L<br />
Adult Female: 20 - 160 IU/L<br />
Newborn: 68 - 580 IU/L<br />
|-<br />
!▲ Increased<br />
|-<br />
|Conditions<br />
|<br />
* Acute myocardial infarction<br />
* Cardiac surgeries<br />
* Cardiac defibrillation<br />
* Myocarditis<br />
* Ventricular arrhythmias<br />
* Cardiac ischemia<br />
|-<br />
|Lab Interferences<br />
|<br />
|-<br />
|Other Factors<br />
|<br />
* Damage to skeletal muscle can also increase CK<br />
* Intramuscular injections can increase CK levels<br />
|}<br />
[[Category:Chemistry]]</div>
Admin
https://medlabwiki.com/index.php?title=Cardiac_Testing&diff=218
Cardiac Testing
2025-03-03T00:14:40Z
<p>Admin: Created page with "Cardiac testing in the lab generally involves monitoring of cardiac markers, which are elevated when damage occurs to the heart. These markers include: * C-reactive protein (CRP) * Creatinine kinase (CK) * Myoglobin * NT-proBNP * Troponins == Overview == * '''Myoglobin is earliest marker''' (but declines quickly) * '''Cardiac troponin 1 is most cardiac-specific''' ** High-sensitivity cTnI used for investigating heart attacks ** Detectable quickly (3-12 hours), and rem..."</p>
<hr />
<div>Cardiac testing in the lab generally involves monitoring of cardiac markers, which are elevated when damage occurs to the heart. These markers include:<br />
<br />
* C-reactive protein (CRP)<br />
* Creatinine kinase (CK)<br />
* Myoglobin<br />
* NT-proBNP<br />
* Troponins<br />
<br />
== Overview ==<br />
<br />
* '''Myoglobin is earliest marker''' (but declines quickly)<br />
* '''Cardiac troponin 1 is most cardiac-specific'''<br />
** High-sensitivity cTnI used for investigating heart attacks<br />
** Detectable quickly (3-12 hours), and remain elevated >1 week<br />
* CK-MB/CK2 is isoenzyme associated with cardiac muscle (but also skeletal muscle)<br />
** Elevation occurs later and lasts longer (~5 days)<br />
<br />
Others<br />
<br />
* CRP is acute inflammatory marker, can also be used to assess future risk for CVD<br />
* NT-proBNP elevated in heart failure<br />
<br />
== C-reactive protein ==<br />
C-reactive protein is an non-specific, acute phase reactant that is produced as a part of inflammatory processes. The assay can be used to investigate a variety of disorders that are associated with inflammation, including infections, autoimmune conditions, necrosis, etc.<br />
<br />
* CRP is generally a better indicator of inflammatory processes than the ESR.<br />
<br />
{| class="wikitable"<br />
|+<br />
! rowspan="2" |C-reactive protein<br />
! colspan="2" |RI: <10 mg/L<br />
|-<br />
!▲ Increased<br />
!▼ Decreased<br />
|-<br />
|Conditions<br />
|<br />
* Bacterial infections<br />
* Surgical complications (e.g., infection, clots)<br />
* Autoimmune diseases (arthritis, Crohn's disease, etc.)<br />
* Vascular diseases<br />
** Including increased risk of cardiovascular ischemia<br />
* Tissue damage<br />
** Acute myocardial infarction<br />
* Malignancy<br />
|<br />
|-<br />
|Lab Interferences<br />
|<br />
|<br />
|-<br />
|Other Factors<br />
|<br />
* Smoking<br />
* Hypertension<br />
* Low HDL/high triglycerides<br />
* Elevated BMI<br />
* Diabetes<br />
* Chronic infections (e.g., gingivitis)<br />
* Medications<br />
|<br />
* Medications, especially anti-inflammatory drugs<br />
* Exercise, weight loss<br />
* Alcohol consumption<br />
|}<br />
<br />
== High-sensitivity C-reactive protein ==<br />
This CRP assay has an increased sensitivity, allowing for the monitoring of low-level inflammation that may indicate future cardiac events.<br />
<br />
* Athermomatous plaques in arteries release inflammatory molecules, making baseline hs-CRP values useful in monitoring risk of future cardiac events in patients with stable or acute coronary diseases.<br />
** Low risk: 0.7 - 1.1 mg/L<br />
** Moderate risk: 1.2 - 1.9 mg/L<br />
** High risk: 2.0 - 3.8 mg/L<br />
* Can be used alongside lipid testing for cardiac risk scores (e.g., Framingham risk score)<br />
<br />
== Creatinine kinase ==<br />
This non-specific enzyme is has 3 isoenzymes that are found within various tissues, including the heart, skeletal muscle, and brain.<br />
<br />
* CK-MM (96-100%)<br />
* '''CK-MB (CK2) (0-6%)'''<br />
* CK-BB (0%)<br />
<br />
CK-MB is the enzyme that is most specific for heart muscle damage.<br />
<br />
* Levels rise 3-6 hours after damage<br />
* After damage stops, peaks 12-24 hours after<br />
* Returns to normal 12-48 hours after peak (4-5 days total)<br />
<br />
{| class="wikitable"<br />
! rowspan="2" |Creatinine Kinase<br />
!Adult Male: 20 - 215 IU/L<br />
Adult Female: 20 - 160 IU/L<br />
Newborn: 68 - 580 IU/L<br />
|-<br />
!▲ Increased<br />
|-<br />
|Conditions<br />
|<br />
* Acute myocardial infarction<br />
* Cardiac surgeries<br />
* Cardiac defibrillation<br />
* Myocarditis<br />
* Ventricular arrhythmias<br />
* Cardiac ischemia<br />
|-<br />
|Lab Interferences<br />
|<br />
|-<br />
|Other Factors<br />
|<br />
* Damage to skeletal muscle can also increase CK<br />
* Intramuscular injections can increase CK levels<br />
|}<br />
[[Category:Chemistry]]</div>
Admin
https://medlabwiki.com/index.php?title=Biochemistry&diff=217
Biochemistry
2025-03-02T23:22:30Z
<p>Admin: </p>
<hr />
<div>== General pages ==<br />
Clinical biochemistry involves diagnostic testing of blood and other body fluids for enzymes, proteins, antibodies, and more for the purposes of monitoring and diagnosing disease.[[Chemistry Specimen Processing]]<br />
<br />
[[Chemistry Calculations]]<br />
<br />
== Clinical instrumentation ==<br />
[[Immunoassays]]<br />
<br />
[[Electrochemical Measurement Systems]] (EMS)<br />
<br />
== Biochemistry by body system ==<br />
[[Cardiac Testing]]<br />
<br />
[[Liver Testing]]<br />
<br />
[[Kidney Testing]]<br />
<br />
== Special topics in biochemistry ==<br />
[[Glucose & Carbohydrates]]<br />
<br />
[[Lipids]]<br />
<br />
[[Enzymes]]<br />
<br />
[[Hormones]]<br />
<br />
[[Electrolytes]]<br />
<br />
[[Osmometry]]<br />
<br />
[[Tumour Markers]]</div>
Admin
https://medlabwiki.com/index.php?title=Chemistry_Calculations&diff=216
Chemistry Calculations
2025-03-02T23:07:38Z
<p>Admin: </p>
<hr />
<div>== Statistics & Quality Control ==<br />
<br />
=== Mean/Average (unit) ===<br />
The mean is the average of a series of numbers. Report to the same units and decimal places as the data.<br />
<br />
<math display="block">\bar{x}=\frac{x_1+x_2+...+x_n}{n}</math><br />
<br />
=== Sample Standard Deviation (same unit as data) ===<br />
Use standard deviation when the '''mean of two methods is the same.''' Report as +1 decimal place more than the data.<br />
<br />
<math display="block">s=\sqrt{\frac{\Sigma(x-\bar{x})^2}{n-1}}</math>where x = data and <math>\bar{x} = \text{Mean}</math><br />
<br />
=== Coefficient of Variation (%) ===<br />
Use coefficient of variation when the '''mean of two methods is different.''' Report to 1 decimal place.<br />
<br />
<math display="block">CV=\frac{SD}{Mean}*100</math><br />
<br />
=== Percent Error (%) ===<br />
Report to 1 decimal place.<br />
<br />
<math display="block">\mathrm{% Error}=\frac{Actual-Theoretical}{Theoretical}*100\mathrm{%}</math><br />
<br />
=== Westgard Rules ===<br />
There are 4 reject rules and 2 warning rules:<br />
<br />
* 1-3s (one control value exceeds the mean ±3 SD)<br />
* 2-2s (two consecutive control values exceed the mean ±2 SD)<br />
* R-4s (when one value exceeds the mean +2 SD and another value exceeds -2 SD '''within the same run''' so that the values are 4 SD different from each other)<br />
* 4-1s (four consecutive control values exceed the mean ±1 SD)<br />
<br />
Warning Rules:<br />
<br />
* 1-2s (one control value exceeds the mean ±2 SD)<br />
* R10x (ten consecutive values fall on one side of the mean)<br />
<br />
=== Specificity Calculation (%) ===<br />
The specificity is the probability that a given person who does not have a condition (i.e., is healthy) would actually test negative.<br />
<br />
<math display="block">Specificity=\frac{\mbox{True Negatives}}{\mbox{True Negatives }+\mbox{ False positives}}</math><br />
<br />
=== Sensitivity Calculation (%) ===<br />
The sensitivity is the probability that a given person who has a condition (e.g., disease) would actually test positive.<br />
<br />
<math display="block">Sensitivity=\frac{\mbox{True Positives}}{\mbox{True Positives }+\mbox{ False negatives}}</math><br />
<br />
=== Negative Predictive Value (%) ===<br />
The negative predictive value (NPV) is a measure of how often someone who tests negative for a disease will not have the disease.<br />
<br />
<math display="block">\mbox{Negative Predictive Value}=\frac{\mbox{True Negatives}}{\mbox{True Negatives }+\mbox{ False negatives}}</math><br />
<br />
=== Positive Preductive Value (%) ===<br />
The positive predictive value (PPV) is a measure of how often someone who tests positive for a disease will actually have the disease.<br />
<br />
<math display="block">\mbox{Positive Predictive Value}=\frac{\mbox{True Positives}}{\mbox{True Positives }+\mbox{ False positives}}</math><br />
<br />
== Blood pH & Respiration ==<br />
<br />
=== Blood pH Calculations (unitless) ===<br />
<math display="block">pH=6.1+log\frac{[HCO^-]}{0.03*P_{CO2}}</math><br />
<br />
OR<br />
<br />
<math display="block">pH=6.1+log\frac{[HCO^-]}{dCO_2}</math><br />
<br />
dCO<sub>2</sub> = dissolved CO<sub>2</sub> (mmol/L)<br />
<br />
PCO<sub>2</sub> = partial pressure CO<sub>2</sub> (mmHg)<br />
<br />
[HCO<sup>-</sup>] = concentration of bicarbonate (mmol/L)<br />
<br />
=== Conversion Between PCO<sub>2</sub> (mmHg) and dCO<sub>2</sub> (mmol/L) ===<br />
<math display="block">dCO_2=PCO_2*0.03</math><br />
<br />
=== Calculation of HCO<sub>3</sub><sup>-</sup> (mmol/L) ===<br />
Used when TCO<sub>2</sub> is measured via a wet or dry methodology.<br />
<br />
<math display="block">[HCO_3^-]=T_{CO_2}-1.2 \mbox{ mmol/L}</math><br />
<br />
== Kidney Function Testing ==<br />
<br />
=== Creatinine Clearance (mL/s) ===<br />
Creatinine clearance is (U*V)/S and the corrected creatinine clearance uses BSA to correct for size/muscle mass.<br />
<br />
<math display="block">CC=\frac{U*V}{S}*\frac{1.73}{BSA}</math><br />
<br />
<math display="block">CC=\frac{\mbox{[Urine Creatinine]}*\mbox{Urine flow}]}{\mbox{[Serum creatinine]}}*\frac{1.73}{\mbox{Body surface area}}</math><br />
<br />
Convert mmol/L to mmol/day:<br />
<br />
<math display="block">\mbox{24h excretion}=\frac{\mbox{24h urine volume }*\mbox{ [Analyte]}}{1000}</math><br />
<br />
U = urine creatinine (μmol/L)<br />
<br />
S = serum creatinine (μmol/L)<br />
<br />
V = urine flow rate (mL/s) - this is the 24h volume (mL) divided by 86 400 seconds per 24h<br />
<br />
BSA = body surface area (m<sup>2</sup>) - calculate using height and weight on nomogram<br />
<br />
=== Creatinine (mmol/d) ===<br />
Used as measure of creatinine levels from 24h urine.<br />
<br />
<math display="block">Creatinine=\frac{V*c}{1000}</math><br />
<br />
<math display="block">=\frac{\mbox{Urine volume }*[Creatinine]}{1000}</math><br />
<br />
=== eGFR Estimated Glomerular Filtration Rate ===<br />
Complicated calculation using standardized serum creatinine and many correction factors for age and gender.<br />
<br />
== Electrolytes & Osmolality ==<br />
<br />
=== Osmolal Gap (Osm/kg) ===<br />
Calculates difference between expected osmolality vs actual osmolality. High osmolar gap may be due to presence of volatile or osmotically active compounds like ethanol, methanol, etc.<br />
<br />
<math display="block">\mbox{Calculated Osmolality}=2*[Na^{2+}]+[Urea]+[Glucose]</math><br />
<br />
From this, the osmolar gap can be calculated:<br />
<br />
<math display="block">\mbox{Osmolar Gap}=\mbox{Measured Osmolality}-\mbox{Calculated Osmolality}</math><br />
<br />
=== Freezing Point Depression (°C) ===<br />
Calculates the freezing temperature based on osmolality.<br />
<br />
<math display="block">\mbox{Osmolality (mmol/kg)}=\frac{\mbox{FP Depression}}{1.86\mbox{°C}}*100</math><br />
<br />
=== Anion Gap - North America (mmol/L) ===<br />
The anion gap estimates the difference in cations vs. anions in blood. It can be used to help investigate acid-base disturbances and issues with electrolyte measurement. Potassium (K<sup>+</sup>) ions are not included in this calculation in North America.<br />
<br />
<math display="block">\mbox{Anion gap}=(Na^+)-(Cl^-+HCO_3^-)</math><br />
<br />
== Dilutions & Concentrations ==<br />
<br />
=== Calculating Dilutions Using Dilution Factors and Total Volume ===<br />
You can determine the amount of solute required for a dilution with a given dilution factor and final (total) volume.<br />
<br />
<math display="block">DF=\frac{V_{total}}{V_{solute}}</math><br />
<br />
<math display="block">V_{solute}=\frac{V_{total}}{DF}</math><br />
<br />
DF = dilution factor (e.g., in a 1:250 dilution, the DF is 250)<br />
<br />
You can then determine the amount of diluent/solvent needed from the calculated volume of solute required.<br />
<br />
<math display="block">V_{diluent}=V_{total}-V_{solute}</math><br />
<br />
== Absorbance & Measurement ==<br />
Determining Unknown Concentration by Absorbance<br />
<br />
<math display="block">[Unknown]=\frac{Abs_u*[Standard]}{Abs_s}</math><br />
[[Category:Calculations]]<br />
__NOEDITSECTION__<br />
[[Category:Chemistry]]</div>
Admin
https://medlabwiki.com/index.php?title=Chemistry_Specimen_Processing&diff=215
Chemistry Specimen Processing
2025-02-27T05:07:37Z
<p>Admin: /* Lab Test Reference Intervals */</p>
<hr />
<div>Separate serum/plasma from blood cells within 2 hours<br />
<br />
* For serum, need to wait for specimen to clot first (20-30 min)<br />
Store samples at 4C when not being run<br />
<br />
For longer-term storage, store at minimum -20C<br />
{| class="wikitable"<br />
|+<br />
!Analyte<br />
!Specimen Type<br />
!Collection Media<br />
!Collection Notes<br />
!Reference Interval<br />
|-<br />
|Sodium<br />
|<br />
|Lithium heparin<br />
|<br />
|135 - 145 mmol/L<br />
|-<br />
|Potassium<br />
|<br />
|Lithium heparin<br />
|<br />
|3.5-5.0 mmol/L<br />
|-<br />
| rowspan="2" |Glucose<br />
|Fasting<br />
|<br />
|<br />
|4.1 - 5.6 mmol/L<br />
|-<br />
|Random<br />
|<br />
|<br />
|<br />
|-<br />
| rowspan="2" |Creatinine<br />
|Urine, 24 hour<br />
|<br />
|<br />
|<br />
|-<br />
|Blood serum<br />
|Lithium heparin<br />
|<br />
|<br />
|-<br />
|Serum Iron<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Ferritin<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Total Iron Binding Capacity<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|% Transferrin Saturation<br />
|<br />
|<br />
|<br />
|20-55%<br />
|-<br />
| rowspan="3" |Urea<br />
|Blood serum or plasma<br />
|Lithium heparin<br />
|<br />
|2.1 - 7.1 mmol/L<br />
|-<br />
|Urine, random<br />
|<br />
|Use thymol preservative and refrigerate<br />
|<br />
|-<br />
|Urine, 24 hour<br />
|<br />
|Use thymol preservative and refrigerate<br />
|430 - 710 mmol/day<br />
|-<br />
| rowspan="2" |Uric Acid<br />
|Blood serum or plasma<br />
|Lithium heparin<br />
|<br />
|<br />
|-<br />
|Urine, 24 hour<br />
|<br />
|<br />
|<br />
|-<br />
|Urinalysis<br />
|Urine, first morning midstream clean-catch preferred<br />
|<br />
|Fresh samples <2h old<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|}<br />
Special Samples:<br />
<br />
* Keep on ice<br />
** Blood gases<br />
** Ammonia<br />
* Protect from light<br />
** Bilirubin<br />
** Vitamin B12<br />
<br />
== Lab Test Reference Intervals ==<br />
{| class="wikitable"<br />
|+<br />
!Test<br />
!Reference Interval<br />
!Clinical Relevance<br />
!Interferences<br />
!Notes<br />
|-<br />
|Sodium<br />
|135 - 145 mmol/L<br />
|<br />
|<br />
|<br />
|-<br />
|Potassium<br />
|3.5 - 5.0 mmol/L<br />
|<br />
|<br />
|<br />
|-<br />
|Chloride<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|pH<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|pO<sub>2</sub><br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|pCO<sub>2</sub><br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|[HCO<sub>3</sub><sup>-</sup>]<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Glucose, fasting<br />
|4.1 - 5.6 mmol/L<br />
|<br />
|<br />
|<br />
|-<br />
|Glucose, random<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Total Bilirubin<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Unconjugated Bilirubin<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Conjugated Bilirubin<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|eGFR<br />
|>2.0 mL/s<br />
|<br />
|<br />
|Preferred over creatinine clearance<br />
|-<br />
|Urine flow rate<br />
|0.05 mL/s<br />
|<br />
|<br />
|<br />
|-<br />
|Creatinine (serum)<br />
|62 - 115 μmol/L (male)<br />
53 - 97 μmol/L (female)<br />
|<br />
| rowspan="3" |<br />
* ↑ Hemolysis<br />
* ↓ Icterus<br />
* ↓ Lipemia<br />
* Ammonium heparin<br />
* Non-specific chromogens<br />
|<br />
|-<br />
|Creatinine (urine, 24h)<br />
|9 - 18 mmol/d (male)<br />
7 - 16 mmol/d (female)<br />
|<br />
|Inaccuracies may arise from improper urine measurement or tubular secretion.<br />
|-<br />
|Creatinine Clearance<br />
|1.42 - 2.08 mL/s (male)<br />
1.24 - 1.92 mL/s (female)<br />
|<br />
|<0.63 mL/s is markedly decreased<br />
High serum creatinine may over-estimate CC.<br />
|}<br />
Blood Gas Results<br />
{| class="wikitable"<br />
!Test<br />
!Reference Interval<br />
!Clinical Relevance<br />
!Notes<br />
|-<br />
|Sodium<br />
|135 - 145 mmol/L<br />
|<br />
|<br />
|-<br />
|Potassium<br />
|3.5 - 5.0 mmol/L<br />
|<br />
|<br />
|-<br />
|Chloride<br />
|<br />
|<br />
|<br />
|-<br />
|pH<br />
|7.35 - 7.45<br />
|<br />
|<br />
|-<br />
|pO<sub>2</sub><br />
|<br />
|<br />
|<br />
|-<br />
|pCO<sub>2</sub><br />
|35 - 45 mmHg<br />
|<br />
|<br />
|-<br />
|[HCO<sub>3</sub><sup>-</sup>]<br />
|21 - 28 mmol/L<br />
|<br />
|<br />
|}<br />
Heme -> bilirubin -> unconjugated bilirubin (transport via albumin) -> conjugated bili -> urobilinogen (in GI) -> urobilin excreted<br />
<br />
Hepatic Jaundice<br />
<br />
* ↑ AST, ALT, GGT <br />
* ALP N/↑<br />
* ↑ Total, unconj., conj. bilirubin<br />
<br />
Obstructive (post-hepatic) jaundice<br />
<br />
* ↑↑ ALP and GGT<br />
* ↑ Bilirubin<br />
* ALT, AST vary<br />
<br />
Enzymes<br />
<br />
* ALT most liver specific<br />
** Except alcoholic cirrhosis AST 2x ALT<br />
* AST more general (liver, skeletal muscle, heart, RBCs)<br />
* GGT sensitive to liver injury, but not specific (high in alcoholic liver cirrhosis)<br />
* LD not specific<br />
* ALP non-specific<br />
* ↓ albumin, ↑ gamma globulins (IgG, IgM hepatitis; IgA alcoholic cirrhosis)<br />
** Beta-gamma bridging<br />
<br />
Pancreatitis<br />
<br />
* Amylase<br />
* Lipase (more specific than amylase)<br />
<br />
Affected by HIL<br />
<br />
* K<sup>+</sup><br />
* LD very sensitive!!! and unstable!!!<br />
* AST<br />
* Bilirubin<br />
** ↓ Hemolysis<br />
** ↑ Lipemia<br />
<br />
Less Affected<br />
<br />
* Na (dilutional effect)<br />
* Cl (dilutional effect)<br />
* ALP<br />
* CK (gross hemolysis false ↑)<br />
<br />
CSF Tubes<br />
<br />
# Chemistry<br />
# Microbiology<br />
# Hematology<br />
# Other (e.g., cytology)<br />
<br />
Hashimoto = low T3,T4 and high TSH<br />
<br />
Grave's = hyperthyroidism = excess T4, low TSH<br />
<br />
Cushing's = high cortisol =<br />
<br />
* High ACTH with ACTH-dependent (pituitary)<br />
* Low ACTH with independent (adrenal cancer, etc.)<br />
* Higher part of the body is high ACTH and dependent (pituitary); lower part of the body is low ACTH and independent (adrenal)<br />
<br />
Cardiac Markers<br />
<br />
* Myoglobin = earliest marker (but declines quickly)<br />
* CK elevated in cardiac and skeletal disorders<br />
** CK-MB/CK2 most specific isoenzyme for cardiac issues (but also skeletal)<br />
* Cardiac troponin 1 is very cardiac-specific!<br />
** High sensitivity cTnI used for investigating heart attacks<br />
** Detectable quickly (3-12 hours), and remain elevated >1 week<br />
* NT-proBNP elevated in heart failure<br />
* CRP acute marker of inflammation, can help evaluate risk for CVD</div>
Admin
https://medlabwiki.com/index.php?title=Chemistry_Specimen_Processing&diff=214
Chemistry Specimen Processing
2025-02-27T01:57:34Z
<p>Admin: </p>
<hr />
<div>Separate serum/plasma from blood cells within 2 hours<br />
<br />
* For serum, need to wait for specimen to clot first (20-30 min)<br />
Store samples at 4C when not being run<br />
<br />
For longer-term storage, store at minimum -20C<br />
{| class="wikitable"<br />
|+<br />
!Analyte<br />
!Specimen Type<br />
!Collection Media<br />
!Collection Notes<br />
!Reference Interval<br />
|-<br />
|Sodium<br />
|<br />
|Lithium heparin<br />
|<br />
|135 - 145 mmol/L<br />
|-<br />
|Potassium<br />
|<br />
|Lithium heparin<br />
|<br />
|3.5-5.0 mmol/L<br />
|-<br />
| rowspan="2" |Glucose<br />
|Fasting<br />
|<br />
|<br />
|4.1 - 5.6 mmol/L<br />
|-<br />
|Random<br />
|<br />
|<br />
|<br />
|-<br />
| rowspan="2" |Creatinine<br />
|Urine, 24 hour<br />
|<br />
|<br />
|<br />
|-<br />
|Blood serum<br />
|Lithium heparin<br />
|<br />
|<br />
|-<br />
|Serum Iron<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Ferritin<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Total Iron Binding Capacity<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|% Transferrin Saturation<br />
|<br />
|<br />
|<br />
|20-55%<br />
|-<br />
| rowspan="3" |Urea<br />
|Blood serum or plasma<br />
|Lithium heparin<br />
|<br />
|2.1 - 7.1 mmol/L<br />
|-<br />
|Urine, random<br />
|<br />
|Use thymol preservative and refrigerate<br />
|<br />
|-<br />
|Urine, 24 hour<br />
|<br />
|Use thymol preservative and refrigerate<br />
|430 - 710 mmol/day<br />
|-<br />
| rowspan="2" |Uric Acid<br />
|Blood serum or plasma<br />
|Lithium heparin<br />
|<br />
|<br />
|-<br />
|Urine, 24 hour<br />
|<br />
|<br />
|<br />
|-<br />
|Urinalysis<br />
|Urine, first morning midstream clean-catch preferred<br />
|<br />
|Fresh samples <2h old<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|}<br />
Special Samples:<br />
<br />
* Keep on ice<br />
** Blood gases<br />
** Ammonia<br />
* Protect from light<br />
** Bilirubin<br />
** Vitamin B12<br />
<br />
== Lab Test Reference Intervals ==<br />
{| class="wikitable"<br />
|+<br />
!Test<br />
!Reference Interval<br />
!Clinical Relevance<br />
!Interferences<br />
!Notes<br />
|-<br />
|Sodium<br />
|135 - 145 mmol/L<br />
|<br />
|<br />
|<br />
|-<br />
|Potassium<br />
|3.5 - 5.0 mmol/L<br />
|<br />
|<br />
|<br />
|-<br />
|Chloride<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|pH<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|pO<sub>2</sub><br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|pCO<sub>2</sub><br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|[HCO<sub>3</sub><sup>-</sup>]<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Glucose, fasting<br />
|4.1 - 5.6 mmol/L<br />
|<br />
|<br />
|<br />
|-<br />
|Glucose, random<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Total Bilirubin<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Unconjugated Bilirubin<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Conjugated Bilirubin<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|eGFR<br />
|>2.0 mL/s<br />
|<br />
|<br />
|Preferred over creatinine clearance<br />
|-<br />
|Urine flow rate<br />
|0.05 mL/s<br />
|<br />
|<br />
|<br />
|-<br />
|Creatinine (serum)<br />
|62 - 115 μmol/L (male)<br />
53 - 97 μmol/L (female)<br />
|<br />
| rowspan="3" |<br />
* ↑ Hemolysis<br />
* ↓ Icterus<br />
* ↓ Lipemia<br />
* Ammonium heparin<br />
* Non-specific chromogens<br />
|<br />
|-<br />
|Creatinine (urine, 24h)<br />
|9 - 18 mmol/d (male)<br />
7 - 16 mmol/d (female)<br />
|<br />
|Inaccuracies may arise from improper urine measurement or tubular secretion.<br />
|-<br />
|Creatinine Clearance<br />
|1.42 - 2.08 mL/s (male)<br />
1.24 - 1.92 mL/s (female)<br />
|<br />
|<0.63 mL/s is markedly decreased<br />
High serum creatinine may over-estimate CC.<br />
|}<br />
Blood Gas Results<br />
{| class="wikitable"<br />
!Test<br />
!Reference Interval<br />
!Clinical Relevance<br />
!Notes<br />
|-<br />
|Sodium<br />
|135 - 145 mmol/L<br />
|<br />
|<br />
|-<br />
|Potassium<br />
|3.5 - 5.0 mmol/L<br />
|<br />
|<br />
|-<br />
|Chloride<br />
|<br />
|<br />
|<br />
|-<br />
|pH<br />
|7.35 - 7.45<br />
|<br />
|<br />
|-<br />
|pO<sub>2</sub><br />
|<br />
|<br />
|<br />
|-<br />
|pCO<sub>2</sub><br />
|35 - 45 mmHg<br />
|<br />
|<br />
|-<br />
|[HCO<sub>3</sub><sup>-</sup>]<br />
|21 - 28 mmol/L<br />
|<br />
|<br />
|}</div>
Admin
https://medlabwiki.com/index.php?title=Chemistry_Specimen_Processing&diff=213
Chemistry Specimen Processing
2025-02-27T01:54:53Z
<p>Admin: </p>
<hr />
<div>Separate serum/plasma from blood cells within 2 hours<br />
<br />
* For serum, need to wait for specimen to clot first (20-30 min)<br />
Store samples at 4C when not being run<br />
<br />
For longer-term storage, store at minimum -20C<br />
{| class="wikitable"<br />
|+<br />
!Analyte<br />
!Specimen Type<br />
!Collection Media<br />
!Collection Notes<br />
!Reference Interval<br />
|-<br />
|Sodium<br />
|<br />
|Lithium heparin<br />
|<br />
|135 - 145 mmol/L<br />
|-<br />
|Potassium<br />
|<br />
|Lithium heparin<br />
|<br />
|3.5-5.0 mmol/L<br />
|-<br />
| rowspan="2" |Glucose<br />
|Fasting<br />
|<br />
|<br />
|4.1 - 5.6 mmol/L<br />
|-<br />
|Random<br />
|<br />
|<br />
|<br />
|-<br />
| rowspan="2" |Creatinine<br />
|Urine, 24 hour<br />
|<br />
|<br />
|<br />
|-<br />
|Blood serum<br />
|Lithium heparin<br />
|<br />
|<br />
|-<br />
|Serum Iron<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Ferritin<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Total Iron Binding Capacity<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|% Transferrin Saturation<br />
|<br />
|<br />
|<br />
|20-55%<br />
|-<br />
| rowspan="3" |Urea<br />
|Blood serum or plasma<br />
|Lithium heparin<br />
|<br />
|2.1 - 7.1 mmol/L<br />
|-<br />
|Urine, random<br />
|<br />
|Use thymol preservative and refrigerate<br />
|<br />
|-<br />
|Urine, 24 hour<br />
|<br />
|Use thymol preservative and refrigerate<br />
|430 - 710 mmol/day<br />
|-<br />
| rowspan="2" |Uric Acid<br />
|Blood serum or plasma<br />
|Lithium heparin<br />
|<br />
|<br />
|-<br />
|Urine, 24 hour<br />
|<br />
|<br />
|<br />
|-<br />
|Urinalysis<br />
|Urine, first morning midstream clean-catch preferred<br />
|<br />
|Fresh samples <2h old<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|}<br />
Special Samples:<br />
<br />
* Keep on ice<br />
** Blood gases<br />
** Ammonia<br />
* Protect from light<br />
** Bilirubin<br />
** Vitamin B12<br />
{| class="wikitable"<br />
|+<br />
!Test<br />
!Reference Interval<br />
!Clinical Relevance<br />
!Interferences<br />
!Notes<br />
|-<br />
|Sodium<br />
|135 - 145 mmol/L<br />
|<br />
|<br />
|<br />
|-<br />
|Potassium<br />
|3.5 - 5.0 mmol/L<br />
|<br />
|<br />
|<br />
|-<br />
|Chloride<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|pH<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|pO<sub>2</sub><br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|pCO<sub>2</sub><br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|[HCO<sub>3</sub><sup>-</sup>]<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Glucose, fasting<br />
|4.1 - 5.6 mmol/L<br />
|<br />
|<br />
|<br />
|-<br />
|Glucose, random<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Total Bilirubin<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Unconjugated Bilirubin<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Conjugated Bilirubin<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|eGFR<br />
|>2.0 mL/s<br />
|<br />
|<br />
|<br />
|-<br />
|Urine flow rate<br />
|0.05 mL/s<br />
|<br />
|<br />
|<br />
|-<br />
|Creatinine (serum)<br />
|62 - 115 μmol/L (male)<br />
53 - 97 μmol/L (female)<br />
|<br />
| rowspan="3" |<br />
* ↑ Hemolysis<br />
* ↓ Icterus<br />
* ↓ Lipemia<br />
* Ammonium heparin<br />
* Non-specific chromogens<br />
|<br />
|-<br />
|Creatinine (urine, 24h)<br />
|9 - 18 mmol/d (male)<br />
7 - 16 mmol/d (female)<br />
|<br />
|<br />
|-<br />
|Creatinine Clearance<br />
|1.42 - 2.08 mL/s (male)<br />
1.24 - 1.92 mL/s (female)<br />
|<br />
|<0.63 mL/s is markedly decreased<br />
High serum creatinine may over-estimate CC.<br />
|}<br />
Blood Gas Results<br />
{| class="wikitable"<br />
!Test<br />
!Reference Interval<br />
!Clinical Relevance<br />
!Notes<br />
|-<br />
|Sodium<br />
|135 - 145 mmol/L<br />
|<br />
|<br />
|-<br />
|Potassium<br />
|3.5 - 5.0 mmol/L<br />
|<br />
|<br />
|-<br />
|Chloride<br />
|<br />
|<br />
|<br />
|-<br />
|pH<br />
|7.35 - 7.45<br />
|<br />
|<br />
|-<br />
|pO<sub>2</sub><br />
|<br />
|<br />
|<br />
|-<br />
|pCO<sub>2</sub><br />
|35 - 45 mmHg<br />
|<br />
|<br />
|-<br />
|[HCO<sub>3</sub><sup>-</sup>]<br />
|21 - 28 mmol/L<br />
|<br />
|<br />
|}</div>
Admin
https://medlabwiki.com/index.php?title=Chemistry_Calculations&diff=212
Chemistry Calculations
2025-02-27T01:20:47Z
<p>Admin: </p>
<hr />
<div>== Statistics & Quality Control ==<br />
<br />
=== Mean/Average (unit) ===<br />
The mean is the average of a series of numbers. Report to the same units and decimal places as the data.<br />
<br />
<math display="block">\bar{x}=\frac{x_1+x_2+...+x_n}{n}</math><br />
<br />
=== Sample Standard Deviation (same unit as data) ===<br />
Use standard deviation when the '''mean of two methods is the same.''' Report as +1 decimal place more than the data.<br />
<br />
<math display="block">s=\sqrt{\frac{\Sigma(x-\bar{x})^2}{n-1}}</math>where x = data and <math>\bar{x} = \text{Mean}</math><br />
<br />
=== Coefficient of Variation (%) ===<br />
Use coefficient of variation when the '''mean of two methods is different.''' Report to 1 decimal place.<br />
<br />
<math display="block">CV=\frac{SD}{Mean}*100</math><br />
<br />
=== Percent Error (%) ===<br />
Report to 1 decimal place.<br />
<br />
<math display="block">\mathrm{% Error}=\frac{Actual-Theoretical}{Theoretical}*100\mathrm{%}</math><br />
<br />
=== Westgard Rules ===<br />
There are 4 reject rules and 2 warning rules:<br />
<br />
* 1-3s (one control value exceeds the mean ±3 SD)<br />
* 2-2s (two consecutive control values exceed the mean ±2 SD)<br />
* R-4s (when one value exceeds the mean +2 SD and another value exceeds -2 SD '''within the same run''' so that the values are 4 SD different from each other)<br />
* 4-1s (four consecutive control values exceed the mean ±1 SD)<br />
<br />
Warning Rules:<br />
<br />
* 1-2s (one control value exceeds the mean ±2 SD)<br />
* R10x (ten consecutive values fall on one side of the mean)<br />
<br />
=== Specificity Calculation (%) ===<br />
The specificity is the probability that a given person who does not have a condition (i.e., is healthy) would actually test negative.<br />
<br />
<math display="block">Specificity=\frac{\mbox{True Negatives}}{\mbox{True Negatives }+\mbox{ False positives}}</math><br />
<br />
=== Sensitivity Calculation (%) ===<br />
The sensitivity is the probability that a given person who has a condition (e.g., disease) would actually test positive.<br />
<br />
<math display="block">Sensitivity=\frac{\mbox{True Positives}}{\mbox{True Positives }+\mbox{ False negatives}}</math><br />
<br />
=== Negative Predictive Value (%) ===<br />
The negative predictive value (NPV) is a measure of how often someone who tests negative for a disease will not have the disease.<br />
<br />
<math display="block">\mbox{Negative Predictive Value}=\frac{\mbox{True Negatives}}{\mbox{True Negatives }+\mbox{ False negatives}}</math><br />
<br />
=== Positive Preductive Value (%) ===<br />
The positive predictive value (PPV) is a measure of how often someone who tests positive for a disease will actually have the disease.<br />
<br />
<math display="block">\mbox{Positive Predictive Value}=\frac{\mbox{True Positives}}{\mbox{True Positives }+\mbox{ False positives}}</math><br />
<br />
== Blood pH & Respiration ==<br />
<br />
=== Blood pH Calculations (unitless) ===<br />
<math display="block">pH=6.1+log\frac{[HCO^-]}{0.03*P_{CO2}}</math><br />
<br />
OR<br />
<br />
<math display="block">pH=6.1+log\frac{[HCO^-]}{dCO_2}</math><br />
<br />
dCO<sub>2</sub> = dissolved CO<sub>2</sub> (mmol/L)<br />
<br />
PCO<sub>2</sub> = partial pressure CO<sub>2</sub> (mmHg)<br />
<br />
[HCO<sup>-</sup>] = concentration of bicarbonate (mmol/L)<br />
<br />
=== Conversion Between PCO<sub>2</sub> (mmHg) and dCO<sub>2</sub> (mmol/L) ===<br />
<math display="block">dCO_2=PCO_2*0.03</math><br />
<br />
=== Calculation of HCO<sub>3</sub><sup>-</sup> (mmol/L) ===<br />
Used when TCO<sub>2</sub> is measured via a wet or dry methodology.<br />
<br />
<math display="block">[HCO_3^-]=T_{CO_2}-1.2 \mbox{ mmol/L}</math><br />
<br />
== Kidney Function Testing ==<br />
<br />
=== Creatinine Clearance (mL/s) ===<br />
Creatinine clearance is (U*V)/S and the corrected creatinine clearance uses BSA to correct for size/muscle mass.<br />
<br />
<math display="block">CC=\frac{U*V}{S}*\frac{1.73}{BSA}</math><br />
<br />
<math display="block">CC=\frac{\mbox{[Urine Creatinine]}*\mbox{Urine flow}]}{\mbox{[Serum creatinine]}}*\frac{1.73}{\mbox{Body surface area}}</math><br />
<br />
Convert mmol/L to mmol/day:<br />
<br />
<math display="block">\mbox{24h excretion}=\frac{\mbox{24h urine volume }*\mbox{ [Analyte]}}{1000}</math><br />
<br />
U = urine creatinine (μmol/L)<br />
<br />
S = serum creatinine (μmol/L)<br />
<br />
V = urine flow rate (mL/s) - this is the 24h volume (mL) divided by 86 400 seconds per 24h<br />
<br />
BSA = body surface area (m<sup>2</sup>) - calculate using height and weight on nomogram<br />
<br />
=== Creatinine (mmol/d) ===<br />
Used as measure of creatinine levels from 24h urine.<br />
<br />
<math display="block">Creatinine=\frac{V*c}{1000}</math><br />
<br />
<math display="block">=\frac{\mbox{Urine volume }*[Creatinine]}{1000}</math><br />
<br />
=== eGFR Estimated Glomerular Filtration Rate ===<br />
Complicated calculation using standardized serum creatinine and many correction factors for age and gender.<br />
<br />
== Electrolytes & Osmolality ==<br />
<br />
=== Osmolal Gap (Osm/kg) ===<br />
Calculates difference between expected osmolality vs actual osmolality. High osmolar gap may be due to presence of volatile or osmotically active compounds like ethanol, methanol, etc.<br />
<br />
<math display="block">\mbox{Calculated Osmolality}=2*[Na^{2+}]+[Urea]+[Glucose]</math><br />
<br />
From this, the osmolar gap can be calculated:<br />
<br />
<math display="block">\mbox{Osmolar Gap}=\mbox{Measured Osmolality}-\mbox{Calculated Osmolality}</math><br />
<br />
=== Freezing Point Depression (°C) ===<br />
Calculates the freezing temperature based on osmolality.<br />
<br />
<math display="block">\mbox{Osmolality (mmol/kg)}=\frac{\mbox{FP Depression}}{1.86\mbox{°C}}*100</math><br />
<br />
=== Anion Gap - North America (mmol/L) ===<br />
The anion gap estimates the difference in cations vs. anions in blood. It can be used to help investigate acid-base disturbances and issues with electrolyte measurement. Potassium (K<sup>+</sup>) ions are not included in this calculation in North America.<br />
<br />
<math display="block">\mbox{Anion gap}=(Na^+)-(Cl^-+HCO_3^-)</math><br />
<br />
== Dilutions & Concentrations ==<br />
<br />
=== Calculating Dilutions Using Dilution Factors and Total Volume ===<br />
You can determine the amount of solute required for a dilution with a given dilution factor and final (total) volume.<br />
<br />
<math display="block">DF=\frac{V_{total}}{V_{solute}}</math><br />
<br />
<math display="block">V_{solute}=\frac{V_{total}}{DF}</math><br />
<br />
DF = dilution factor (e.g., in a 1:250 dilution, the DF is 250)<br />
<br />
You can then determine the amount of diluent/solvent needed from the calculated volume of solute required.<br />
<br />
<math display="block">V_{diluent}=V_{total}-V_{solute}</math><br />
<br />
== Absorbance & Measurement ==<br />
Determining Unknown Concentration by Absorbance<br />
<br />
<math display="block">[Unknown]=\frac{Abs_u*[Standard]}{Abs_s}</math><br />
[[Category:Calculations]]<br />
__NOEDITSECTION__</div>
Admin
https://medlabwiki.com/index.php?title=Chemistry_Calculations&diff=211
Chemistry Calculations
2025-02-26T15:46:53Z
<p>Admin: </p>
<hr />
<div>== Statistics & Quality Control ==<br />
<br />
=== Mean/Average (unit) ===<br />
The mean is the average of a series of numbers. Report to the same units and decimal places as the data.<br />
<br />
<math display="block">\bar{x}=\frac{x_1+x_2+...+x_n}{n}</math><br />
<br />
=== Sample Standard Deviation (same unit as data) ===<br />
Use standard deviation when the '''mean of two methods is the same.''' Report as +1 decimal place more than the data.<br />
<br />
<math display="block">s=\sqrt{\frac{\Sigma(x-\bar{x})^2}{n-1}}</math>where x = data and <math>\bar{x} = \text{Mean}</math><br />
<br />
=== Coefficient of Variation (%) ===<br />
Use coefficient of variation when the '''mean of two methods is different.''' Report to 1 decimal place.<br />
<br />
<math display="block">CV=\frac{SD}{Mean}*100</math><br />
<br />
=== Percent Error (%) ===<br />
Report to 1 decimal place.<br />
<br />
<math display="block">\mathrm{% Error}=\frac{Actual-Theoretical}{Theoretical}*100\mathrm{%}</math><br />
<br />
=== Westgard Rules ===<br />
There are 4 reject rules and 2 warning rules:<br />
<br />
* 1-3s (one control value exceeds the mean ±3 SD)<br />
* 2-2s (two consecutive control values exceed the mean ±2 SD)<br />
* R-4s (when one value exceeds the mean +2 SD and another value exceeds -2 SD '''within the same run''' so that the values are 4 SD different from each other)<br />
* 4-1s (four consecutive control values exceed the mean ±1 SD)<br />
<br />
Warning Rules:<br />
<br />
* 1-2s (one control value exceeds the mean ±2 SD)<br />
* R10x (ten consecutive values fall on one side of the mean)<br />
<br />
=== Specificity Calculation (%) ===<br />
The specificity is the probability that a given person who does not have a condition (i.e., is healthy) would actually test negative.<br />
<br />
<math display="block">Specificity=\frac{\mbox{True Negatives}}{\mbox{True Negatives }+\mbox{ False positives}}</math><br />
<br />
=== Sensitivity Calculation (%) ===<br />
The sensitivity is the probability that a given person who has a condition (e.g., disease) would actually test positive.<br />
<br />
<math display="block">Sensitivity=\frac{\mbox{True Positives}}{\mbox{True Positives }+\mbox{ False negatives}}</math><br />
<br />
=== Negative Predictive Value (%) ===<br />
The negative predictive value (NPV) is a measure of how often someone who tests negative for a disease will not have the disease.<br />
<br />
<math display="block">\mbox{Negative Predictive Value}=\frac{\mbox{True Negatives}}{\mbox{True Negatives }+\mbox{ False negatives}}</math><br />
<br />
=== Positive Preductive Value (%) ===<br />
The positive predictive value (PPV) is a measure of how often someone who tests positive for a disease will actually have the disease.<br />
<br />
<math display="block">\mbox{Positive Predictive Value}=\frac{\mbox{True Positives}}{\mbox{True Positives }+\mbox{ False positives}}</math><br />
<br />
== Blood pH & Respiration ==<br />
<br />
=== Blood pH Calculations (unitless) ===<br />
<math display="block">pH=6.1+log\frac{[HCO^-]}{0.03*P_{CO2}}</math><br />
<br />
OR<br />
<br />
<math display="block">pH=6.1+log\frac{[HCO^-]}{dCO_2}</math><br />
<br />
dCO<sub>2</sub> = dissolved CO<sub>2</sub> (mmol/L)<br />
<br />
PCO<sub>2</sub> = partial pressure CO<sub>2</sub> (mmHg)<br />
<br />
[HCO<sup>-</sup>] = concentration of bicarbonate (mmol/L)<br />
<br />
=== Conversion Between PCO<sub>2</sub> (mmHg) and dCO<sub>2</sub> (mmol/L) ===<br />
<math display="block">dCO_2=PCO_2*0.03</math><br />
<br />
== Kidney Function Testing ==<br />
<br />
=== Creatinine Clearance (mL/s) ===<br />
Creatinine clearance is (U*V)/S and the corrected creatinine clearance uses BSA to correct for size/muscle mass.<br />
<br />
<math display="block">CC=\frac{U*V}{S}*\frac{1.73}{BSA}</math><br />
<br />
<math display="block">CC=\frac{\mbox{[Urine Creatinine]}*\mbox{Urine flow}]}{\mbox{[Serum creatinine]}}*\frac{1.73}{\mbox{Body surface area}}</math><br />
<br />
Convert mmol/L to mmol/day:<br />
<br />
<math display="block">\mbox{24h excretion}=\frac{\mbox{24h urine volume }*\mbox{ [Analyte]}}{1000}</math><br />
<br />
U = urine creatinine (μmol/L)<br />
<br />
S = serum creatinine (μmol/L)<br />
<br />
V = urine flow rate (mL/s) - this is the 24h volume (mL) divided by 86 400 seconds per 24h<br />
<br />
BSA = body surface area (m<sup>2</sup>) - calculate using height and weight on nomogram<br />
<br />
=== Creatinine (mmol/d) ===<br />
Used as measure of creatinine levels from 24h urine.<br />
<br />
<math display="block">Creatinine=\frac{V*c}{1000}</math><br />
<br />
<math display="block">=\frac{\mbox{Urine volume }*[Creatinine]}{1000}</math><br />
<br />
=== eGFR Estimated Glomerular Filtration Rate ===<br />
Complicated calculation using standardized serum creatinine and many correction factors for age and gender.<br />
<br />
== Electrolytes & Osmolality ==<br />
<br />
=== Osmolal Gap (Osm/kg) ===<br />
Calculates difference between expected osmolality vs actual osmolality. High osmolar gap may be due to presence of volatile or osmotically active compounds like ethanol, methanol, etc.<br />
<br />
<math display="block">\mbox{Calculated Osmolality}=2*[Na^{2+}]+[Urea]+[Glucose]</math><br />
<br />
From this, the osmolar gap can be calculated:<br />
<br />
<math display="block">\mbox{Osmolar Gap}=\mbox{Measured Osmolality}-\mbox{Calculated Osmolality}</math><br />
<br />
=== Freezing Point Depression (°C) ===<br />
Calculates the freezing temperature based on osmolality.<br />
<br />
<math display="block">\mbox{Osmolality (mmol/kg)}=\frac{\mbox{FP Depression}}{1.86\mbox{°C}}*100</math><br />
<br />
=== Anion Gap (mmol/L) ===<br />
The anion gap measures the difference in cations vs. anions in blood. It can be used to help investigate acid-base disturbances and issues with electrolyte measurement.<br />
<br />
<math display="block">\mbox{Anion gap}=(Na^++K^+)-(Cl^-+HCO_3^-)</math><br />
<br />
== Dilutions & Concentrations ==<br />
<br />
=== Calculating Dilutions Using Dilution Factors and Total Volume ===<br />
You can determine the amount of solute required for a dilution with a given dilution factor and final (total) volume.<br />
<br />
<math display="block">DF=\frac{V_{total}}{V_{solute}}</math><br />
<br />
<math display="block">V_{solute}=\frac{V_{total}}{DF}</math><br />
<br />
DF = dilution factor (e.g., in a 1:250 dilution, the DF is 250)<br />
<br />
You can then determine the amount of diluent/solvent needed from the calculated volume of solute required.<br />
<br />
<math display="block">V_{diluent}=V_{total}-V_{solute}</math><br />
<br />
== Absorbance & Measurement ==<br />
Determining Unknown Concentration by Absorbance<br />
<br />
<math display="block">[Unknown]=\frac{Abs_u*[Standard]}{Abs_s}</math><br />
[[Category:Calculations]]<br />
__NOEDITSECTION__</div>
Admin
https://medlabwiki.com/index.php?title=Chemistry_Calculations&diff=210
Chemistry Calculations
2025-02-26T08:43:48Z
<p>Admin: </p>
<hr />
<div>== Statistics & Quality Control ==<br />
<br />
=== Mean/Average (unit) ===<br />
The mean is the average of a series of numbers. Report to the same units and decimal places as the data.<br />
<br />
<math display="block">\bar{x}=\frac{x_1+x_2+...+x_n}{n}</math><br />
<br />
=== Sample Standard Deviation (same unit as data) ===<br />
Use standard deviation when the '''mean of two methods is the same.''' Report as +1 decimal place more than the data.<br />
<br />
<math display="block">s=\sqrt{\frac{\Sigma(x-\bar{x})^2}{n-1}}</math>where x = data and <math>\bar{x} = \text{Mean}</math><br />
<br />
=== Coefficient of Variation (%) ===<br />
Use coefficient of variation when the '''mean of two methods is different.''' Report to 1 decimal place.<br />
<br />
<math display="block">CV=\frac{SD}{Mean}*100</math><br />
<br />
=== Percent Error (%) ===<br />
Report to 1 decimal place.<br />
<br />
<math display="block">\mathrm{% Error}=\frac{Actual-Theoretical}{Theoretical}*100\mathrm{%}</math><br />
<br />
=== Westgard Rules ===<br />
There are 4 reject rules and 2 warning rules:<br />
<br />
* 1-3s (one control value exceeds the mean ±3 SD)<br />
* 2-2s (two consecutive control values exceed the mean ±2 SD)<br />
* R-4s (when one value exceeds the mean +2 SD and another value exceeds -2 SD '''within the same run''' so that the values are 4 SD different from each other)<br />
* 4-1s (four consecutive control values exceed the mean ±1 SD)<br />
<br />
Warning Rules:<br />
<br />
* 1-2s (one control value exceeds the mean ±2 SD)<br />
* R10x (ten consecutive values fall on one side of the mean)<br />
<br />
=== Specificity Calculation (%) ===<br />
The specificity is the probability that a given person who does not have a condition (i.e., is healthy) would actually test negative.<br />
<br />
<math display="block">Specificity=\frac{\mbox{True Negatives}}{\mbox{True Negatives }+\mbox{ False positives}}</math><br />
<br />
=== Sensitivity Calculation (%) ===<br />
The sensitivity is the probability that a given person who has a condition (e.g., disease) would actually test positive.<br />
<br />
<math display="block">Sensitivity=\frac{\mbox{True Positives}}{\mbox{True Positives }+\mbox{ False negatives}}</math><br />
<br />
=== Negative Predictive Value (%) ===<br />
The negative predictive value (NPV) is a measure of how often someone who tests negative for a disease will not have the disease.<br />
<br />
<math display="block">\mbox{Negative Predictive Value}=\frac{\mbox{True Negatives}}{\mbox{True Negatives }+\mbox{ False negatives}}</math><br />
<br />
=== Positive Preductive Value (%) ===<br />
The positive predictive value (PPV) is a measure of how often someone who tests positive for a disease will actually have the disease.<br />
<br />
<math display="block">\mbox{Positive Predictive Value}=\frac{\mbox{True Positives}}{\mbox{True Positives }+\mbox{ False positives}}</math><br />
<br />
== Blood pH & Respiration ==<br />
<br />
=== Blood pH Calculations (unitless) ===<br />
<math display="block">pH=6.1+log\frac{[HCO^-]}{0.03*P_{CO2}}</math><br />
<br />
dCO<sub>2</sub> = dissolved CO<sub>2</sub><br />
<br />
PCO<sub>2</sub> = partial pressure CO<sub>2</sub><br />
<br />
[HCO<sup>-</sup>] = concentration of bicarbonate<br />
<br />
== Kidney Function Testing ==<br />
<br />
=== Creatinine Clearance (mL/s) ===<br />
Creatinine clearance is (U*V)/S and the corrected creatinine clearance uses BSA to correct for size/muscle mass.<br />
<br />
<math display="block">CC=\frac{U*V}{S}*\frac{1.73}{BSA}</math><br />
<br />
<math display="block">CC=\frac{\mbox{[Urine Creatinine]}*\mbox{Urine flow}]}{\mbox{[Serum creatinine]}}*\frac{1.73}{\mbox{Body surface area}}</math><br />
<br />
Convert mmol/L to mmol/day:<br />
<br />
<math display="block">\mbox{24h excretion}=\frac{\mbox{24h urine volume }*\mbox{ [Analyte]}}{1000}</math><br />
<br />
U = urine creatinine (μmol/L)<br />
<br />
S = serum creatinine (μmol/L)<br />
<br />
V = urine flow rate (mL/s) - this is the 24h volume (mL) divided by 86 400 seconds per 24h<br />
<br />
BSA = body surface area (m<sup>2</sup>) - calculate using height and weight on nomogram<br />
<br />
=== Creatinine (mmol/d) ===<br />
Used as measure of creatinine levels from 24h urine.<br />
<br />
<math display="block">Creatinine=\frac{V*c}{1000}</math><br />
<br />
<math display="block">=\frac{\mbox{Urine volume }*[Creatinine]}{1000}</math><br />
<br />
=== eGFR Estimated Glomerular Filtration Rate ===<br />
Complicated calculation using standardized serum creatinine and many correction factors for age and gender.<br />
<br />
== Electrolytes & Osmolality ==<br />
<br />
=== Osmolal Gap (Osm/kg) ===<br />
Calculates difference between expected osmolality vs actual osmolality. High osmolar gap may be due to presence of volatile or osmotically active compounds like ethanol, methanol, etc.<br />
<br />
<math display="block">\mbox{Calculated Osmolality}=2*[Na^{2+}]+[Urea]+[Glucose]</math><br />
<br />
From this, the osmolar gap can be calculated:<br />
<br />
<math display="block">\mbox{Osmolar Gap}=\mbox{Measured Osmolality}-\mbox{Calculated Osmolality}</math><br />
<br />
=== Freezing Point Depression (°C) ===<br />
Calculates the freezing temperature based on osmolality.<br />
<br />
<math display="block">\mbox{Osmolality (mmol/kg)}=\frac{\mbox{FP Depression}}{1.86\mbox{°C}}*100</math><br />
<br />
=== Anion Gap (mmol/L) ===<br />
The anion gap measures the difference in cations vs. anions in blood. It can be used to help investigate acid-base disturbances and issues with electrolyte measurement.<br />
<br />
<math display="block">\mbox{Anion gap}=(Na^++K^+)-(Cl^-+HCO_3^-)</math><br />
<br />
== Dilutions & Concentrations ==<br />
<br />
=== Calculating Dilutions Using Dilution Factors and Total Volume ===<br />
You can determine the amount of solute required for a dilution with a given dilution factor and final (total) volume.<br />
<br />
<math display="block">DF=\frac{V_{total}}{V_{solute}}</math><br />
<br />
<math display="block">V_{solute}=\frac{V_{total}}{DF}</math><br />
<br />
DF = dilution factor (e.g., in a 1:250 dilution, the DF is 250)<br />
<br />
You can then determine the amount of diluent/solvent needed from the calculated volume of solute required.<br />
<br />
<math display="block">V_{diluent}=V_{total}-V_{solute}</math><br />
<br />
== Absorbance & Measurement ==<br />
Determining Unknown Concentration by Absorbance<br />
<br />
<math display="block">[Unknown]=\frac{Abs_u*[Standard]}{Abs_s}</math><br />
[[Category:Calculations]]<br />
__NOEDITSECTION__</div>
Admin
https://medlabwiki.com/index.php?title=Chemistry_Specimen_Processing&diff=209
Chemistry Specimen Processing
2025-02-26T08:39:17Z
<p>Admin: </p>
<hr />
<div>Separate serum/plasma from blood cells within 2 hours<br />
<br />
* For serum, need to wait for specimen to clot first (20-30 min)<br />
Store samples at 4C when not being run<br />
<br />
For longer-term storage, store at minimum -20C<br />
{| class="wikitable"<br />
|+<br />
!Analyte<br />
!Specimen Type<br />
!Collection Media<br />
!Collection Notes<br />
!Reference Interval<br />
|-<br />
|Sodium<br />
|<br />
|Lithium heparin<br />
|<br />
|135 - 145 mmol/L<br />
|-<br />
|Potassium<br />
|<br />
|Lithium heparin<br />
|<br />
|3.5-5.0 mmol/L<br />
|-<br />
| rowspan="2" |Glucose<br />
|Fasting<br />
|<br />
|<br />
|4.1 - 5.6 mmol/L<br />
|-<br />
|Random<br />
|<br />
|<br />
|<br />
|-<br />
| rowspan="2" |Creatinine<br />
|Urine, 24 hour<br />
|<br />
|<br />
|<br />
|-<br />
|Blood serum<br />
|Lithium heparin<br />
|<br />
|<br />
|-<br />
|Serum Iron<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Ferritin<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Total Iron Binding Capacity<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|% Transferrin Saturation<br />
|<br />
|<br />
|<br />
|20-55%<br />
|-<br />
| rowspan="3" |Urea<br />
|Blood serum or plasma<br />
|Lithium heparin<br />
|<br />
|2.1 - 7.1 mmol/L<br />
|-<br />
|Urine, random<br />
|<br />
|Use thymol preservative and refrigerate<br />
|<br />
|-<br />
|Urine, 24 hour<br />
|<br />
|Use thymol preservative and refrigerate<br />
|430 - 710 mmol/day<br />
|-<br />
| rowspan="2" |Uric Acid<br />
|Blood serum or plasma<br />
|Lithium heparin<br />
|<br />
|<br />
|-<br />
|Urine, 24 hour<br />
|<br />
|<br />
|<br />
|-<br />
|Urinalysis<br />
|Urine, first morning midstream clean-catch preferred<br />
|<br />
|Fresh samples <2h old<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|}<br />
Special Samples:<br />
<br />
* Keep on ice<br />
** Blood gases<br />
** Ammonia<br />
* Protect from light<br />
** Bilirubin<br />
** Vitamin B12<br />
{| class="wikitable"<br />
|+<br />
!Test<br />
!Reference Interval<br />
!Clinical Relevance<br />
!Notes<br />
|-<br />
|Sodium<br />
|135 - 145 mmol/L<br />
|<br />
|<br />
|-<br />
|Potassium<br />
|3.5 - 5.0 mmol/L<br />
|<br />
|<br />
|-<br />
|Chloride<br />
|<br />
|<br />
|<br />
|-<br />
|Glucose, fasting<br />
|4.1 - 5.6 mmol/L<br />
|<br />
|<br />
|-<br />
|Glucose, random<br />
|<br />
|<br />
|<br />
|-<br />
|Total Bilirubin<br />
|<br />
|<br />
|<br />
|-<br />
|Unconjugated Bilirubin<br />
|<br />
|<br />
|<br />
|-<br />
|Conjugated Bilirubin<br />
|<br />
|<br />
|<br />
|}</div>
Admin
https://medlabwiki.com/index.php?title=Red_Blood_Cell_Conditions&diff=208
Red Blood Cell Conditions
2025-02-25T20:32:03Z
<p>Admin: </p>
<hr />
<div>There are a variety of conditions that contribute to abnormal RBC function or counts.<br />
{| class="wikitable"<br />
|+<br />
!Condition<br />
!Physiology<br />
!RBC<br />
!HGB<br />
!HCT<br />
!MCV<br />
!MCH<br />
!MCHC<br />
!RDW<br />
!Morphology<br />
!Followup Tests<br />
|-<br />
|Blood loss/hemorrhage <br />
|<br />
|N/↓<br />
|N<br />
|N<br />
|N<br />
|N<br />
|N<br />
|N<br />
|Normal<br />
|<br />
|-<br />
|Iron Deficiency Anemia<br />
|Insufficient erythropoiesis<br />
<br />
* Inadequate iron intake<br />
* Chronic blood loss<br />
|N/↓<br />
|N/↓<br />
|↓<br />
|↓<br />
|↓<br />
|↓<br />
|↑<br />
|Hypo/micro<br />
<br />
* Ovals, pencils<br />
* Tears, targets (occasional)<br />
|<br />
|-<br />
|Anemia of Chronic Inflammation<br />
|Insufficient erythropoiesis<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|Normal or Hypo/micro<br />
|<br />
|-<br />
| rowspan="2" |Sideroblastic Anemia<br />
|Ineffective erythropoiesis<br />
<br />
* Deficient protoporphyrin synthesis<br />
* RBCs made but iron doesn't bind to ring<br />
|↓<br />
|↓<br />
|↓<br />
|N/↓<br />
|N/↓<br />
|N/↓<br />
|↑<br />
|Dual population<br />
<br />
# Normochromic/normocytic<br />
# Hypo/micro<br />
<br />
Pappenheimers<br />
|Ringed sideroblasts in BM<br />
|-<br />
|Lead poisoning (secondary)<br />
<br />
* Certain drugs and heavy metals<br />
|↓<br />
|↓<br />
|↓<br />
|N/↓<br />
|N/↓<br />
|N/'''↓'''<br />
|N<br />
|Normal OR hypo/micro<br />
<br />
* Stomatocytes<br />
* Coarse basophilic stippling<br />
|<br />
|-<br />
|Iron Overload<br />
|<br />
* Inherited conditions (hereditary hemochromatosis)<br />
* Excess iron accumulation from treatment (e.g., blood transfusion)<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Thalassemia<br />
|Ineffective erythropoiesis<br />
|N/↑<br />
|N/↓<br />
|N/↓<br />
|↓↓<br />
|↓<br />
|N/↓<br />
|N<br />
|Hypo/micro<br />
<br />
* Targets<br />
* Tears<br />
* Increased polychromasia<br />
* Basophilic stipping<br />
* NRBCs<br />
|<br />
|-<br />
| rowspan="2" |Megaloblastic Anemia<br />
|Ineffective erythropoiesis<br />
<br />
* Vitamin B12 deficiency<br />
* Folic acid deficiency<br />
* Certain cancers or drugs<br />
Causes nuclear-cytoplasmic asynchrony<br />
|↓<br />
|↓<br />
|↓<br />
|↑↑<br />
|↑<br />
|N<br />
|↑<br />
|Macrocytic/normochromic<br />
<br />
* Pancytopenia<br />
* Oval macrocytes<br />
* Hypersegmented neutrophils<br />
* Tears, schistocytes, microspherocytes, targets<br />
* HJ bodies, basophilic stippling<br />
* NRBCs<br />
|Cell fragmentation/lysis<br />
<br />
* ↑ Serum bilirubin<br />
* ↑ LDH<br />
* Vitamin testing<br />
* Antibody assays<br />
|-<br />
|Pernicious anemia<br />
<br />
* Autoimmune cause (destruction of parietal cells)<br />
|↓<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
| rowspan="5" |Macrocytic non-megaloblastic anemia<br />
|Liver disease<br />
|<br />
|<br />
|<br />
|↑<br />
|<br />
|N<br />
|<br />
|Macrocytic/normochromic<br />
<br />
* Round macrocytes<br />
* Targets<br />
|<br />
* Liver panel<br />
* Bilirubin<br />
* Coagulation testing<br />
|-<br />
|Chronic alcoholism<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|Macrocytic<br />
<br />
* Round macrocytes<br />
* Spur cells<br />
* Stomatocytes?<br />
|<br />
|-<br />
|Normal newborn<br />
|↑<br />
|↑<br />
|↑<br />
|↑<br />
|<br />
|<br />
|<br />
|Macrocytic/normochromic<br />
<br />
* Macrocytes<br />
<br />
* Burrs<br />
* Fragments<br />
* Spherocytes<br />
* Increased poly<br />
* NRBCs<br />
|<br />
|-<br />
|Reticulocytosis<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Bone marrow failure<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Aplastic Anemia<br />
|Insufficient erythropoiesis<br />
<br />
* Hypocellularity due to autoimmune destruction<br />
|<br />
|<br />
|<br />
|↑<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|}<br />
Insufficient Erythropoiesis<br />
<br />
* Iron deficiency anemia<br />
* Erythropoietin deficiency (renal disease)<br />
* Loss of erythroid precursors<br />
** Aplastic anemia (autoimmune)<br />
** Infection<br />
** Destruction/suppression of erythroid precursors (cancers, granulomas, fibrosis)<br />
Anemias<br />
<br />
* Ineffective erythropoiesis<br />
** Defective precursors made that are destroyed or function poorly<br />
* Insufficient erythropoiesis<br />
* Blood loss (acute or chronic)<br />
* Increased RBC destruction (hemolytic anemia)<br />
** Shortened cell survival<br />
** Intrinsic RBC defects<br />
** Extrinsic RBC defects<br />
Hemoglobin & Size<br />
<br />
* Normocytic and normochromic<br />
** Hemoglobinopathies<br />
*** Sickle cell<br />
*** Other abnormal hemoglobins<br />
** Infections (including malaria and sepsis)<br />
** Hemolytic anemias<br />
*** HUS, DIC, TTP<br />
** Membrane disorders (hereditary sph<br />
** Enzyme disorders (PK and G6PD deficiencies)<br />
** Poisons, toxins, drugs<br />
** Aplastic anemia<br />
** Burns<br />
** Hemorrhage<br />
* Hypochromic and microcytic<br />
** IDA<br />
** Sideroblastic anemia<br />
** Thalassemia (globin chain deficiency)<br />
** Anemia of chronic inflammation (severe)<br />
* Macrocytic and normochromic<br />
** Megaloblastic anemia (B12 or folate deficiency)<br />
** Liver disease</div>
Admin
https://medlabwiki.com/index.php?title=Microbiology_Quick_Reference&diff=207
Microbiology Quick Reference
2025-02-25T16:47:08Z
<p>Admin: /* Enterococcus sp. */</p>
<hr />
<div>== Microbiology Agars ==<br />
{| class="wikitable"<br />
|+<br />
!Agar<br />
!Enrichment<br />
!Selective<br />
!Differential Features<br />
!Use<br />
|-<br />
|Blood<br />
|5-10% sheep blood<br />
|<br />
|Shows hemolysis<br />
|General growth medium<br />
|-<br />
|Chocolate<br />
|5-10% lysed sheep blood<br />
2% hemoglobin + supplements<br />
|<br />
|<br />
|Growth of fastidious organisms<br />
|-<br />
|CNA<br />
|5-10% sheep blood<br />
|Gram positives grow<br />
<br />
* Colistin<br />
* Naladixic acid<br />
|Shows hemolysis<br />
|Growth of gram positives and yeast<br />
|-<br />
|MacConkey<br />
|<br />
|Gram negatives grow<br />
<br />
* Bile salts<br />
* Crystal violet<br />
|Shows lactose fermentation<br />
|Grow of gram negatives<br />
|}<br />
{| class="wikitable"<br />
!Agar<br />
!Features<br />
!Use<br />
|-<br />
|Meuller Hinton<br />
|<br />
|<br />
|-<br />
|MH + Sheep's blood<br />
|<br />
* Enrichment: sheep blood<br />
|AST for specific organisms<br />
<br />
* ''Streptococcus pneumoniae''<br />
|-<br />
|Thioglycollate broth<br />
|<br />
* Enrichment: hemin & vitamin K<br />
* Differential: O<sub>2</sub> use based on location of growth in tube<br />
|General growth medium, allows presumption of atmospheric growth conditions<br />
|-<br />
|Enrichment Media<br />
|<br />
* Usually broth<br />
* Grows fastidious or a specific organism from mixed specimens<br />
* Contain differential reagents to suppress normal flora for a short period of time<br />
** Requires subculture within ~ 12-18h<br />
|<br />
* Selenite broth<br />
* Tetrathionate broth<br />
* Brain-heart Infusion broth<br />
* Cooked meat broth<br />
|-<br />
|Sorbitol MacConkey<br />
|<br />
* Selective: for gram negatives<br />
* Differential: sorbitol fermentation<br />
|Enterohemorrhagic ''E. coli'' (non-sorbitol fermenters) vs other ''E. coli'' (sorbitol fermenters)<br />
|-<br />
|Salmonella-Shigella<br />
|<br />
* Selective: bile salts, sodium citrate, brilliant green<br />
** Selects for gram negative enteric pathogens<br />
* Differential: lactose fermentation + H<sub>2</sub>S production<br />
|Isolate enteric pathogens<br />
|-<br />
|Hektoen Agar<br />
|<br />
* Selective: bile salts<br />
** Selects for gram negative, mostly enteric pathogens<br />
* Differential: lactose, sucrose, and salicin fermentation + H<sub>2</sub>S production<br />
|Isolate enteric pathogens<br />
|-<br />
|Cefsulodin Irgasan Novobiocin (CIN)<br />
|<br />
* Selective: cefsulodin, irgasan, novobiocin, sodium desoxycholate, crystal violet<br />
** Inhibit gram + and normal stool flora<br />
* Differential: mannitol fermentation<br />
|Isolate ''Yersinia enterocolitica''<br />
|-<br />
|Campylobacter agar<br />
|<br />
* Enrichment: 10% sheep blood<br />
* Selective: <br />
** vancomycin (inhibit gram +)<br />
** amphotericin B + polymyxin B (inhibit yeast/fungus)<br />
** trimethoprim (prevent ''Proteus'' swarming)<br />
** cefoperazone (inhibit gram -)<br />
** Sodium bisulfite (creates microaerophillic environment)<br />
|Isolate ''Campylobacter''<br />
|-<br />
|<br />
|<br />
|<br />
|-<br />
|Mannitol salt agar<br />
|<br />
* Selective: 7.5% salt<br />
** Selects for halophiles<br />
* Differential: mannitol fermentation<br />
|Screen for ''Staphylococcus aureus''<br />
|-<br />
|New York City agar<br />
|<br />
* Enrichment: lysed blood, yeast dialysate, and plasma<br />
* Selective: vancomycin, colistin, amphotericin B, and trimethoprim <br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|}<br />
Yeasts<br />
<br />
* Sabourand agar<br />
* Cornmeal agar (especially for Candida spp.)<br />
<br />
Chromogenic Agars<br />
<br />
Staphlyococcus aureus<br />
<br />
* MRSA Select agar<br />
* Denim blue agar<br />
<br />
Streptococcus agalactiae (Group B Strep)<br />
<br />
* Brilliance GBS agar<br />
Candida<br />
<br />
* CandiSelect<br />
* Brilliance Candida<br />
<br />
''Corynebacterium diptheriae''<br />
<br />
* Hoyle's meagar<br />
* Loeffler's<br />
* Tinsdale agar<br />
<br />
== Specimen Collection ==<br />
Stool O&P<br />
<br />
* Unfixed<br />
* 10% formalin (general-purpose)<br />
* PVA polyvinyl alcohol (PCR and staining)<br />
* SAF sodium acetate-acetic acid-formalin (concentration and staining)<br />
Stool<br />
<br />
* Cary-Blair media<br />
<br />
GBS Screen<br />
<br />
* Vaginal-rectal swab<br />
* Todd-Hewitt broth with gentamicin and nalidixic acid to suppress other flora<br />
<br />
== Stains ==<br />
* Gram stain<br />
* Ziehl-Neelsen (acid fast)<br />
** Uses heat for uptake of carbolfuchsin<br />
* Kinyoun (acid fast)<br />
** Higher phenol concentration for uptake of carbolfuchsin<br />
* Auramine/Auramine-Rhodamine (acid fast)<br />
** fluorescent dye binds to mycolic acids<br />
* Acridine Orange (organisms without cell wall)<br />
** fluorescent dye binds to nucleic acid in cells<br />
** useful for organisms without cell wall (e.g., ''Mycoplasma'')<br />
* Calcofluor white (fungi)<br />
** Fluorescent dye binds to cellulose and chitin<br />
<br />
'''K'''inyoun = '''cold''', '''Acrid'''ine = nucleic '''acids''', '''C'''alcofluor = '''c'''hitin<br />
<br />
== Biochemical Tests ==<br />
{| class="wikitable"<br />
|+<br />
!Test<br />
!Purpose<br />
!Mechanism<br />
!Results<br />
|-<br />
|Hugh-Leifson Oxidation/Fermentation Test<br />
|Determines if organism can metabolize carbohydrates<br />
|Incubate tubes with 1% glucose + peptones<br />
Check for pH change in aerobic and anaerobic tubes<br />
<br />
* Fermenter: both +<br />
* Oxidizer: aerobic + only<br />
* Non-fermenter/oxidizer: both -<br />
|Positive: yellow<br />
Negative: green<br />
|-<br />
|ONPG<br />
|Differentiate late lactose fermenters from non-lactose fermenters<br />
<br />
* LLF: have β-galactosidase but not permease to allow cell uptake (may mutate or turn gene on after exposure to lactose)<br />
* NLF: no β-galactosidase (can't utilized lactose)<br />
|Use ONPG disk, which is similar to lactose but small enough to diffuse without permease<br />
|Positive LLF: any yellow<br />
Negative NLF: colourless<br />
|-<br />
|TSI (Triple Sugar Iron)<br />
|Detect fermentation of glucose, lactose, and/or sucrose<br />
Detect production of gases and H<sub>2</sub>S<br />
|0.1% glucose is used up first, then either:<br />
<br />
* Non-fermenters use peptones (alkaline in slant)<br />
* Fermenters use lactose and/or sucrose (acid in both butt and slant)<br />
|Glucose only: NA/A (pink slant, yellow butt)<br />
Multiple carbohydrates: A/A (yellow slant and butt)<br />
Aerobic organism (no fermentation): NA/NC (red slant and butt)<br />
May also produce gas and/or H<sub>2</sub>S<br />
|-<br />
|MRVP<br />
|Used to determine type of pyruvate fermentation pathway used<br />
<br />
* MR uses mixed-acid pathway<br />
* VP uses 2,3-butanediol pathway<br />
|Mixed acid fermentation produces acid end-products (lactic acid and acetic acid), causing pH change<br />
2,3-butanediol pathway produces acetoin<br />
|<br />
|-<br />
|Decarboxylation<br />
|<br />
|<br />
|<br />
|-<br />
|Arginine Dihydrolase<br />
|<br />
|<br />
|<br />
|-<br />
|Phenylalanine Deaminase (PPD)<br />
|Used to test for phenylalanine deaminase<br />
<br />
* Present in gram negative bacilli<br />
|<br />
|Positive: green<br />
Negative: yellow<br />
|-<br />
|Simmon's Citrate<br />
|<br />
|<br />
|Positive: blue or green with growth<br />
Negative: green, no growth<br />
|-<br />
|Gelatin test<br />
|<br />
|<br />
|<br />
|-<br />
|Indole<br />
|<br />
|<br />
|<br />
|-<br />
|Sulfide-Indole-Motility (SIM)<br />
|<br />
|<br />
|<br />
|-<br />
|Nitrate Test<br />
|Determines whether organism has nitrate reductase to produce O<sub>2</sub> anaerobically<br />
|Nitrate reductase converts nitrate -> nitrite (NO<sub>2</sub>)<br />
Some organisms further break down nitrite to nitrogen gas<br />
|If red at first tube = nitrites positive<br />
If not red, then but add zinc<br />
<br />
* Red = negative (original nitrates present)<br />
* No colour = positive (nitrite reduced to N2)<br />
|-<br />
|Urea Test<br />
|<br />
|<br />
|<br />
|}<br />
<br />
== Organism Testing ==<br />
{| class="wikitable"<br />
|+<br />
!Test<br />
!Positive QC<br />
!Negative QC<br />
!Uses<br />
|-<br />
|Catalase<br />
|''Staphylococcus spp.''<br />
|''Streptococcus spp.''<br />
|<br />
|-<br />
|Coagulase<br />
| rowspan="2" |''S. aureus''<br />
| rowspan="2" |Other ''Staphylococcus''<br />
|<br />
|-<br />
|Staphaureux (Latex agglutination)<br />
|<br />
|-<br />
|PYR<br />
|<br />
* ''S. lugdunensis''<br />
* ''Enterococcus''<br />
|<br />
* ''S. aureus''<br />
* ''Strep. bovis''<br />
|<br />
|}<br />
<br />
==== ''Staphylococcus'' species ====<br />
''Staphylococcus aureus''<br />
<br />
* GPC clusters<br />
* Catalase +<br />
* Tube Coagulase + (forms clot in plasma due to Staphylocoagulase)<br />
* Staphaureux +<br />
<br />
If coagulase/Staphaureux negative, then CoNS:<br />
<br />
* ''S. lugdunensis'': PYR +, ORN +<br />
** Has clumping factor that '''can cause weak false positives'''!<br />
* ''S. saprophyticus'' (females 12-60): Novobiocin resistant (≤16 mm)<br />
* Others: ''S. epidermidis'', ''S. hominis'', other CoNS<br />
Related Species (''Micrococcus, Stomatococcus, Planococcus'')<br />
<br />
* Often normal flora<br />
* Similar test results to ''Staphylococcus'' spp.<br />
<br />
==== ''Streptococcus'' species ====<br />
<br />
* GPC pairs & chains<br />
* Catalase -<br />
<br />
Lancefield grouping mainly used for ID<br />
{| class="wikitable"<br />
|+<br />
!Lancefield Grouping<br />
!Organism<br />
!Features<br />
!Clinical Relevance<br />
|-<br />
|Group A<br />
|''S. pyogenes''<br />
|<br />
* Beta-heme (large zone)<br />
* PYR +<br />
* Bacitracin S<br />
* Hippurate hydrolysis neg<br />
|iGAS<br />
|-<br />
|Group B<br />
|''S. agalactiae''<br />
|<br />
* Beta-heme (narrow zone)<br />
* Hippurate +<br />
* Bacitracin R<br />
* CAMP test + (enhanced hemolysis when near beta-heme ''S. aureus'')<br />
|Neonatal infections<br />
|-<br />
| rowspan="2" |Group D<br />
|''S. bovis''<br />
|<br />
* Non-heme<br />
* '''PYR -'''<br />
* '''Bile esculin +'''<br />
|<br />
* Sepsis, sub-acute endocarditis, meningitis<br />
* UTIs<br />
* Association with GI carcinomas<br />
|-<br />
|Enterococcus<br />
<br />
* '''''E. faecalis''''' '''(most common)'''<br />
* '''''E. faecium'' (majority of VREs)'''<br />
* ''E. gallinarum''<br />
* ''E. casseliflavus''<br /><br />
|<br />
* Non-heme, possibly very small beta-heme on some media<br />
* '''PYR +'''<br />
* '''Bile esculin +'''<br />
|<br />
|-<br />
|Group C<br />
| rowspan="2" |''Streptococcus dysgalactiae'' subsp ''equisimilis''<br />
| rowspan="2" |Beta-heme (large zone)<br />
| rowspan="2" |Normally commensal<br />
Possibly cause pharyngitis<br />
|-<br />
|Group G<br />
|-<br />
|Non-groupable<br />
|''S. pneumoniae''<br />
|<br />
* Alpha-heme<br />
* "Checkerboard" colonial appearance<br />
* Bile soluble<br />
* Optochin sensitive (≥14mm)<br />
|<br />
* Otitis media<br />
* Sinusitis<br />
* Pneumonia<br />
* Meningitis<br />
* Etc.<br />
|-<br />
|Various/non-groupable<br />
|Viridans Streptococci<br />
<br />
* ''S. mitis'', ''S. mutans, S. salivarius, S. bovis, S. anginosus''<br />
|<br />
* Most alpha-heme, but also beta- and non-heme<br />
*<br />
|<br />
|}<br />
<br />
==== ''Enterococcus'' sp. ====<br />
Organisms of infection control concern<br />
<br />
''E. faecalis''<br />
<br />
* PYR +<br />
* Bile esculin +<br />
* Arabinose -<br />
* MGP -<br />
<br />
''E. faecium''<br />
<br />
* PYR +<br />
* Bile esculin +<br />
* Arabinose +<br />
* MGP -<br />
<br />
Other ''Enterococci'' (no infection control concern)<br />
<br />
''E. gallinarum''<br />
<br />
* MGP +<br />
<br />
''E. casseliflavus''<br />
<br />
==== Enterobacterales ====<br />
<br />
* GNB, non-spore formers<br />
* Oxidase -<br />
* Reduce nitrates → nitrites<br />
* Ferment carbohydrates<br />
* All motile at 37C except ''Klebsiella, Shigella, Yersinia''<br />
<br />
''E coli''<br />
<br />
Klebsiella<br />
<br />
* Mucoid (capsule)<br />
* Non-motile<br />
<br />
Proteus<br />
<br />
* Swarming motility<br />
* PPD +<br />
* Urea +<br />
* H2S +<br />
<br />
Providencia<br />
<br />
* H2S -<br />
<br />
Morganella<br />
<br />
* H2S -<br />
<br />
Serratia<br />
<br />
* Some species produce red pigment<br />
* ONPG + (LLF)<br />
* DNAse +<br />
<br />
Citrobacter<br />
<br />
Edwardsiella<br />
<br />
Enterobacter<br />
<br />
Pantoea<br />
<br />
Salmonella<br />
<br />
* NLF<br />
* H2S +<br />
<br />
Shigella<br />
<br />
* NLF<br />
* H2S -<br />
* Non-motile<br />
* Latex group testing (A, B, C, D)<br />
<br />
E. coli O157<br />
<br />
* LF usually<br />
* Non-sorbitol fermenter<br />
* Otherwise, similar to other E. coli<br />
* Serology (O157:H7 antisera)<br />
<br />
Yersinia<br />
<br />
* NLF<br />
* Non-motile<br />
* Bullseye on CIN agar (darker red/pink middle, light pink rim)<br />
* Grows at RT and 4C<br />
<br />
== Antibiotic Susceptibility Testing ==<br />
MRSA<br />
<br />
* Penicillins bind to PBP (penicillin binding protein) = inhibits cell wall formation<br />
* MRSAs have mecA gene encoding PBP2a<br />
** PBP2a resistant to ALL beta-lactams<br />
*Test using oxacillin screen and Kirby-Bauer (cefoxitin)<br />
<br />
BORSA (Borderline Oxacillin Resistant ''Staphylococcus aureus'')<br />
<br />
* '''NOT''' due to mecA (therefore, have altered PBP but '''NOT''' PBP2a)<br />
* Due to superproduction of beta-lactamase<br />
* MIC above oxacillin breakpoints (>4 μg/mL), but don't grow on oxacillin screen plates<br />
<br />
VISA<br />
<br />
* Vancomycin MIC breakpoint 4-8 μg/mL<br />
* Possibly due to thickened cell wall, trapping antibiotic<br />
* Test using vancomycin screen<br />
<br />
VRSA<br />
<br />
* Vancomycin MIC breakpoint >8 μg/mL<br />
* vanA resistance from plasmids or transposons (e.g., from VREs)<br />
* Test using vancomycin screen<br />
VRE<br />
<br />
* vanA or vanB associated with outbreaks ''(E. faecalis'' and ''E. faecium'')<br />
* vanC intrinsic - not associated with outbreaks (''E. gallinarum'' and ''E. casseliflavus'')<br />
<br />
D-Test<br />
<br />
* Test for inducible clindamycin resistance<br />
** Presence of ''erm'' gene<br />
** Causes flattening of zone<br />
<br />
== Mycology ==<br />
* Malassezia furfur = Tinea versicolour = budding yeast and hyphae in 10% KOH ("spaghetti and meatballs")<br />
* Candida albicans = polymorphic, chlamydospore +, germ tube +, urea -<br />
* Candida auris = germ tube -<br />
* Cryptococcus = germ tube -, india ink +, urea +<br />
<br />
== Parasitology ==<br />
* Definitive/true host = where parasite develops into sexually mature (adult) form<br />
* Intermediate/secondary host = in-between host where parasite is sexually immature (e.g., larvae)<br />
* Entamoeba histolytica = spoke-like central karyosome(s)<br />
* Trichomonas vaginalis = one nuclei (often oval and to one side), flagella<br />
* Balantidium coli = large, ciliated<br />
* Schistosoma = egg with prominent spine/spike<br />
* Enterobius vermicularis = pinworm, egg is elongated oval with one side flattened<br />
* Strongyloides = larvae migrating through agar<br />
<br />
== Polymerase Chain Reaction ==<br />
<br />
* Taq polymerase used along with dNTPs (nucleotides for elongation), and primers (DNA or RNA sequence of interest)<br />
* Buffer pH at 8.0-9.5, include salts MgCl<sub>2</sub> and KCl<br />
* Amplified through multiple cycles (usually 25-30)<br />
* 95C denature - 60C anneal - 72C extend<br />
* qPCR provides amplification and detection together<br />
** detect products as they're produced<br />
** use fluorescent dye<br />
*** SYBR green or Taqman probe<br />
** SYBR green binds to any double-stranded DNA and fluoresces (more DNA produced = more fluorescence)<br />
** Taqman is more specific, and binds to a specific target section<br />
*** 5' fluorescent dye and 3' quencher<br />
*** No fluorescence when dye and quencher are close together<br />
*** During PCR, the extension of polymerase will cut the Taqman probe with an exonuclease, releasing the fluorescent probe<br />
*** As the probe is cut away from the quencher, a signal is released<br />
*** As amplification continues, more probes are separated from the quencher resulting in a larger signal<br />
** Get amplification curve over ~ 40 cycles<br />
*** Baseline phase (little fluorescent signal)<br />
*** Exponential phase as PCR product amplifies significantly ~ cycles 16-25<br />
*** Stationary phase once components are used up and no further amplification occurs<br />
** Threshold line is the point where there is a certain level of fluorescence above the background signal (set per instrument)<br />
** Cycle threshold (Ct) is the amount of cycles required to reach the threshold line<br />
*** If there's less target DNA/RNA present, it will take more cycles to amplify to this level = higher Ct<br />
*** If there's more target DNA/RNA present, it will take fewer cycles to reach this level = lower Ct<br />
*** Can use known standards to get absolute quantitation of target present by comparing the curves<br />
<br />
== MALDI-ToF ==<br />
Matrix-assisted laser desorption ionization time-of-flight<br />
<br />
* Laser vapourizes complex molecules into ionized protein molecules<br />
** Desorption removes molecules from sample<br />
** Ionization produces positively charged proteins that move through mass spec tube<br />
* Matrix (cinnamic acid) absorbs energy and protects sample<br />
* Measure mass-to-charge (m/z) ratio of molecules<br />
* Generates mass spectrum based on the flight time (speed) of the molecules = mass of ions<br />
** Smaller ions move faster<br />
* Compare results to database of known organisms</div>
Admin
https://medlabwiki.com/index.php?title=Microbiology_Quick_Reference&diff=206
Microbiology Quick Reference
2025-02-25T04:08:04Z
<p>Admin: /* Organism Testing */</p>
<hr />
<div>== Microbiology Agars ==<br />
{| class="wikitable"<br />
|+<br />
!Agar<br />
!Enrichment<br />
!Selective<br />
!Differential Features<br />
!Use<br />
|-<br />
|Blood<br />
|5-10% sheep blood<br />
|<br />
|Shows hemolysis<br />
|General growth medium<br />
|-<br />
|Chocolate<br />
|5-10% lysed sheep blood<br />
2% hemoglobin + supplements<br />
|<br />
|<br />
|Growth of fastidious organisms<br />
|-<br />
|CNA<br />
|5-10% sheep blood<br />
|Gram positives grow<br />
<br />
* Colistin<br />
* Naladixic acid<br />
|Shows hemolysis<br />
|Growth of gram positives and yeast<br />
|-<br />
|MacConkey<br />
|<br />
|Gram negatives grow<br />
<br />
* Bile salts<br />
* Crystal violet<br />
|Shows lactose fermentation<br />
|Grow of gram negatives<br />
|}<br />
{| class="wikitable"<br />
!Agar<br />
!Features<br />
!Use<br />
|-<br />
|Meuller Hinton<br />
|<br />
|<br />
|-<br />
|MH + Sheep's blood<br />
|<br />
* Enrichment: sheep blood<br />
|AST for specific organisms<br />
<br />
* ''Streptococcus pneumoniae''<br />
|-<br />
|Thioglycollate broth<br />
|<br />
* Enrichment: hemin & vitamin K<br />
* Differential: O<sub>2</sub> use based on location of growth in tube<br />
|General growth medium, allows presumption of atmospheric growth conditions<br />
|-<br />
|Enrichment Media<br />
|<br />
* Usually broth<br />
* Grows fastidious or a specific organism from mixed specimens<br />
* Contain differential reagents to suppress normal flora for a short period of time<br />
** Requires subculture within ~ 12-18h<br />
|<br />
* Selenite broth<br />
* Tetrathionate broth<br />
* Brain-heart Infusion broth<br />
* Cooked meat broth<br />
|-<br />
|Sorbitol MacConkey<br />
|<br />
* Selective: for gram negatives<br />
* Differential: sorbitol fermentation<br />
|Enterohemorrhagic ''E. coli'' (non-sorbitol fermenters) vs other ''E. coli'' (sorbitol fermenters)<br />
|-<br />
|Salmonella-Shigella<br />
|<br />
* Selective: bile salts, sodium citrate, brilliant green<br />
** Selects for gram negative enteric pathogens<br />
* Differential: lactose fermentation + H<sub>2</sub>S production<br />
|Isolate enteric pathogens<br />
|-<br />
|Hektoen Agar<br />
|<br />
* Selective: bile salts<br />
** Selects for gram negative, mostly enteric pathogens<br />
* Differential: lactose, sucrose, and salicin fermentation + H<sub>2</sub>S production<br />
|Isolate enteric pathogens<br />
|-<br />
|Cefsulodin Irgasan Novobiocin (CIN)<br />
|<br />
* Selective: cefsulodin, irgasan, novobiocin, sodium desoxycholate, crystal violet<br />
** Inhibit gram + and normal stool flora<br />
* Differential: mannitol fermentation<br />
|Isolate ''Yersinia enterocolitica''<br />
|-<br />
|Campylobacter agar<br />
|<br />
* Enrichment: 10% sheep blood<br />
* Selective: <br />
** vancomycin (inhibit gram +)<br />
** amphotericin B + polymyxin B (inhibit yeast/fungus)<br />
** trimethoprim (prevent ''Proteus'' swarming)<br />
** cefoperazone (inhibit gram -)<br />
** Sodium bisulfite (creates microaerophillic environment)<br />
|Isolate ''Campylobacter''<br />
|-<br />
|<br />
|<br />
|<br />
|-<br />
|Mannitol salt agar<br />
|<br />
* Selective: 7.5% salt<br />
** Selects for halophiles<br />
* Differential: mannitol fermentation<br />
|Screen for ''Staphylococcus aureus''<br />
|-<br />
|New York City agar<br />
|<br />
* Enrichment: lysed blood, yeast dialysate, and plasma<br />
* Selective: vancomycin, colistin, amphotericin B, and trimethoprim <br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|}<br />
Chromogenic Agars<br />
<br />
Staphlyococcus aureus<br />
<br />
* MRSA Select agar<br />
* Denim blue agar<br />
<br />
Streptococcus agalactiae (Group B Strep)<br />
<br />
* Brilliance GBS agar<br />
<br />
== Specimen Collection ==<br />
Stool O&P<br />
<br />
* Unfixed<br />
* 10% formalin (general-purpose)<br />
* PVA polyvinyl alcohol (PCR and staining)<br />
* SAF sodium acetate-acetic acid-formalin (concentration and staining)<br />
Stool<br />
<br />
* Cary-Blair media<br />
<br />
GBS Screen<br />
<br />
* Vaginal-rectal swab<br />
* Todd-Hewitt broth with gentamicin and nalidixic acid to suppress other flora<br />
<br />
== Stains ==<br />
* Gram stain<br />
* Ziehl-Neelsen (acid fast)<br />
** Uses heat for uptake of carbolfuchsin<br />
* Kinyoun (acid fast)<br />
** Higher phenol concentration for uptake of carbolfuchsin<br />
* Auramine/Auramine-Rhodamine (acid fast)<br />
** fluorescent dye binds to mycolic acids<br />
* Acridine Orange (organisms without cell wall)<br />
** fluorescent dye binds to nucleic acid in cells<br />
** useful for organisms without cell wall (e.g., ''Mycoplasma'')<br />
* Calcofluor white (fungi)<br />
** Fluorescent dye binds to cellulose and chitin<br />
<br />
'''K'''inyoun = '''cold''', '''Acrid'''ine = nucleic '''acids''', '''C'''alcofluor = '''c'''hitin<br />
<br />
== Biochemical Tests ==<br />
{| class="wikitable"<br />
|+<br />
!Test<br />
!Purpose<br />
!Mechanism<br />
!Results<br />
|-<br />
|Hugh-Leifson Oxidation/Fermentation Test<br />
|Determines if organism can metabolize carbohydrates<br />
|Incubate tubes with 1% glucose + peptones<br />
Check for pH change in aerobic and anaerobic tubes<br />
<br />
* Fermenter: both +<br />
* Oxidizer: aerobic + only<br />
* Non-fermenter/oxidizer: both -<br />
|Positive: yellow<br />
Negative: green<br />
|-<br />
|ONPG<br />
|Differentiate late lactose fermenters from non-lactose fermenters<br />
<br />
* LLF: have β-galactosidase but not permease to allow cell uptake (may mutate or turn gene on after exposure to lactose)<br />
* NLF: no β-galactosidase (can't utilized lactose)<br />
|Use ONPG disk, which is similar to lactose but small enough to diffuse without permease<br />
|Positive LLF: any yellow<br />
Negative NLF: colourless<br />
|-<br />
|TSI (Triple Sugar Iron)<br />
|Detect fermentation of glucose, lactose, and/or sucrose<br />
Detect production of gases and H<sub>2</sub>S<br />
|0.1% glucose is used up first, then either:<br />
<br />
* Non-fermenters use peptones (alkaline in slant)<br />
* Fermenters use lactose and/or sucrose (acid in both butt and slant)<br />
|Glucose only: NA/A (pink slant, yellow butt)<br />
Multiple carbohydrates: A/A (yellow slant and butt)<br />
Aerobic organism (no fermentation): NA/NC (red slant and butt)<br />
May also produce gas and/or H<sub>2</sub>S<br />
|-<br />
|MRVP<br />
|Used to determine type of pyruvate fermentation pathway used<br />
<br />
* MR uses mixed-acid pathway<br />
* VP uses 2,3-butanediol pathway<br />
|Mixed acid fermentation produces acid end-products (lactic acid and acetic acid), causing pH change<br />
2,3-butanediol pathway produces acetoin<br />
|<br />
|-<br />
|Decarboxylation<br />
|<br />
|<br />
|<br />
|-<br />
|Arginine Dihydrolase<br />
|<br />
|<br />
|<br />
|-<br />
|Phenylalanine Deaminase (PPD)<br />
|Used to test for phenylalanine deaminase<br />
<br />
* Present in gram negative bacilli<br />
|<br />
|Positive: green<br />
Negative: yellow<br />
|-<br />
|Simmon's Citrate<br />
|<br />
|<br />
|Positive: blue or green with growth<br />
Negative: green, no growth<br />
|-<br />
|Gelatin test<br />
|<br />
|<br />
|<br />
|-<br />
|Indole<br />
|<br />
|<br />
|<br />
|-<br />
|Sulfide-Indole-Motility (SIM)<br />
|<br />
|<br />
|<br />
|-<br />
|Nitrate Test<br />
|Determines whether organism has nitrate reductase to produce O<sub>2</sub> anaerobically<br />
|Nitrate reductase converts nitrate -> nitrite (NO<sub>2</sub>)<br />
Some organisms further break down nitrite to nitrogen gas<br />
|If red at first tube = nitrites positive<br />
If not red, then but add zinc<br />
<br />
* Red = negative (original nitrates present)<br />
* No colour = positive (nitrite reduced to N2)<br />
|-<br />
|Urea Test<br />
|<br />
|<br />
|<br />
|}<br />
<br />
== Organism Testing ==<br />
{| class="wikitable"<br />
|+<br />
!Test<br />
!Positive QC<br />
!Negative QC<br />
!Uses<br />
|-<br />
|Catalase<br />
|''Staphylococcus spp.''<br />
|''Streptococcus spp.''<br />
|<br />
|-<br />
|Coagulase<br />
| rowspan="2" |''S. aureus''<br />
| rowspan="2" |Other ''Staphylococcus''<br />
|<br />
|-<br />
|Staphaureux (Latex agglutination)<br />
|<br />
|-<br />
|PYR<br />
|<br />
* ''S. lugdunensis''<br />
* ''Enterococcus''<br />
|<br />
* ''S. aureus''<br />
* ''Strep. bovis''<br />
|<br />
|}<br />
<br />
==== ''Staphylococcus'' species ====<br />
''Staphylococcus aureus''<br />
<br />
* GPC clusters<br />
* Catalase +<br />
* Tube Coagulase + (forms clot in plasma due to Staphylocoagulase)<br />
* Staphaureux +<br />
<br />
If coagulase/Staphaureux negative, then CoNS:<br />
<br />
* ''S. lugdunensis'': PYR +, ORN +<br />
** Has clumping factor that '''can cause weak false positives'''!<br />
* ''S. saprophyticus'' (females 12-60): Novobiocin resistant (≤16 mm)<br />
* Others: ''S. epidermidis'', ''S. hominis'', other CoNS<br />
Related Species (''Micrococcus, Stomatococcus, Planococcus'')<br />
<br />
* Often normal flora<br />
* Similar test results to ''Staphylococcus'' spp.<br />
<br />
==== ''Streptococcus'' species ====<br />
<br />
* GPC pairs & chains<br />
* Catalase -<br />
<br />
Lancefield grouping mainly used for ID<br />
{| class="wikitable"<br />
|+<br />
!Lancefield Grouping<br />
!Organism<br />
!Features<br />
!Clinical Relevance<br />
|-<br />
|Group A<br />
|''S. pyogenes''<br />
|<br />
* Beta-heme (large zone)<br />
* PYR +<br />
* Bacitracin S<br />
* Hippurate hydrolysis neg<br />
|iGAS<br />
|-<br />
|Group B<br />
|''S. agalactiae''<br />
|<br />
* Beta-heme (narrow zone)<br />
* Hippurate +<br />
* Bacitracin R<br />
* CAMP test + (enhanced hemolysis when near beta-heme ''S. aureus'')<br />
|Neonatal infections<br />
|-<br />
| rowspan="2" |Group D<br />
|''S. bovis''<br />
|<br />
* Non-heme<br />
* '''PYR -'''<br />
* '''Bile esculin +'''<br />
|<br />
* Sepsis, sub-acute endocarditis, meningitis<br />
* UTIs<br />
* Association with GI carcinomas<br />
|-<br />
|Enterococcus<br />
<br />
* '''''E. faecalis''''' '''(most common)'''<br />
* '''''E. faecium'' (majority of VREs)'''<br />
* ''E. gallinarum''<br />
* ''E. casseliflavus''<br /><br />
|<br />
* Non-heme, possibly very small beta-heme on some media<br />
* '''PYR +'''<br />
* '''Bile esculin +'''<br />
|<br />
|-<br />
|Group C<br />
| rowspan="2" |''Streptococcus dysgalactiae'' subsp ''equisimilis''<br />
| rowspan="2" |Beta-heme (large zone)<br />
| rowspan="2" |Normally commensal<br />
Possibly cause pharyngitis<br />
|-<br />
|Group G<br />
|-<br />
|Non-groupable<br />
|''S. pneumoniae''<br />
|<br />
* Alpha-heme<br />
* "Checkerboard" colonial appearance<br />
* Bile soluble<br />
* Optochin sensitive (≥14mm)<br />
|<br />
* Otitis media<br />
* Sinusitis<br />
* Pneumonia<br />
* Meningitis<br />
* Etc.<br />
|-<br />
|Various/non-groupable<br />
|Viridans Streptococci<br />
<br />
* ''S. mitis'', ''S. mutans, S. salivarius, S. bovis, S. anginosus''<br />
|<br />
* Most alpha-heme, but also beta- and non-heme<br />
*<br />
|<br />
|}<br />
<br />
==== ''Enterococcus'' sp. ====<br />
Organisms of infection control concern<br />
<br />
''E. faecalis''<br />
<br />
* PYR +<br />
* Bile esculin +<br />
* Arabinose -<br />
* MGP -<br />
<br />
''E. faecium''<br />
<br />
* PYR +<br />
* Bile esculin +<br />
* Arabinose +<br />
* MGP -<br />
<br />
Other ''Enterococci'' (no infection control concern)<br />
<br />
''E. gallinarum''<br />
<br />
* MGP +<br />
<br />
''E. casseliflavus''<br />
<br />
==== Enterobacterales ====<br />
<br />
* GNB, non-spore formers<br />
* Oxidase -<br />
* Reduce nitrates → nitrites<br />
* Ferment carbohydrates<br />
* All motile at 37C except ''Klebsiella, Shigella, Yersinia''<br />
<br />
''E coli''<br />
<br />
Klebsiella<br />
<br />
* Mucoid (capsule)<br />
* Non-motile<br />
<br />
Proteus<br />
<br />
* Swarming motility<br />
* PPD +<br />
* Urea +<br />
* H2S +<br />
<br />
Providencia<br />
<br />
* H2S -<br />
<br />
Morganella<br />
<br />
* H2S -<br />
<br />
Serratia<br />
<br />
* Some species produce red pigment<br />
* ONPG + (LLF)<br />
* DNAse +<br />
<br />
Citrobacter<br />
<br />
Edwardsiella<br />
<br />
Enterobacter<br />
<br />
Pantoea<br />
<br />
Salmonella<br />
<br />
* NLF<br />
* H2S +<br />
<br />
Shigella<br />
<br />
* NLF<br />
* H2S -<br />
* Non-motile<br />
* Latex group testing (A, B, C, D)<br />
<br />
E. coli O157<br />
<br />
* LF usually<br />
* Non-sorbitol fermenter<br />
* Otherwise, similar to other E. coli<br />
* Serology (O157:H7 antisera)<br />
<br />
Yersinia<br />
<br />
* NLF<br />
* Non-motile<br />
* Bullseye on CIN agar (darker red/pink middle, light pink rim)<br />
* Grows at RT and 4C<br />
<br />
== Antibiotic Susceptibility Testing ==<br />
MRSA<br />
<br />
* Penicillins bind to PBP (penicillin binding protein) = inhibits cell wall formation<br />
* MRSAs have mecA gene encoding PBP2a<br />
** PBP2a resistant to ALL beta-lactams<br />
*Test using oxacillin screen and Kirby-Bauer (cefoxitin)<br />
<br />
BORSA (Borderline Oxacillin Resistant ''Staphylococcus aureus'')<br />
<br />
* '''NOT''' due to mecA (therefore, have altered PBP but '''NOT''' PBP2a)<br />
* Due to superproduction of beta-lactamase<br />
* MIC above oxacillin breakpoints (>4 μg/mL), but don't grow on oxacillin screen plates<br />
<br />
VISA<br />
<br />
* Vancomycin MIC breakpoint 4-8 μg/mL<br />
* Possibly due to thickened cell wall, trapping antibiotic<br />
* Test using vancomycin screen<br />
<br />
VRSA<br />
<br />
* Vancomycin MIC breakpoint >8 μg/mL<br />
* vanA resistance from plasmids or transposons (e.g., from VREs)<br />
* Test using vancomycin screen<br />
VRE<br />
<br />
* vanA or vanB associated with outbreaks ''(E. faecalis'' and ''E. faecium'')<br />
* vanC intrinsic - not associated with outbreaks (''E. gallinarum'' and ''E. casseliflavus'')<br />
<br />
D-Test<br />
<br />
* Test for inducible clindamycin resistance<br />
** Presence of ''erm'' gene<br />
** Causes flattening of zone<br />
<br />
== Mycology ==<br />
* Malassezia furfur = Tinea versicolour = budding yeast and hyphae in 10% KOH ("spaghetti and meatballs")<br />
* Candida albicans = polymorphic, chlamydospore +, germ tube +, urea -<br />
* Candida auris = germ tube -<br />
* Cryptococcus = germ tube -, india ink +, urea +<br />
<br />
== Parasitology ==<br />
* Definitive/true host = where parasite develops into sexually mature (adult) form<br />
* Intermediate/secondary host = in-between host where parasite is sexually immature (e.g., larvae)<br />
* Entamoeba histolytica = spoke-like central karyosome(s)<br />
* Trichomonas vaginalis = one nuclei (often oval and to one side), flagella<br />
* Balantidium coli = large, ciliated<br />
* Schistosoma = egg with prominent spine/spike<br />
* Enterobius vermicularis = pinworm, egg is elongated oval with one side flattened<br />
* Strongyloides = larvae migrating through agar<br />
<br />
== Polymerase Chain Reaction ==<br />
<br />
* Taq polymerase used along with dNTPs (nucleotides for elongation), and primers (DNA or RNA sequence of interest)<br />
* Buffer pH at 8.0-9.5, include salts MgCl<sub>2</sub> and KCl<br />
* Amplified through multiple cycles (usually 25-30)<br />
* 95C denature - 60C anneal - 72C extend<br />
* qPCR provides amplification and detection together<br />
** detect products as they're produced<br />
** use fluorescent dye<br />
*** SYBR green or Taqman probe<br />
** SYBR green binds to any double-stranded DNA and fluoresces (more DNA produced = more fluorescence)<br />
** Taqman is more specific, and binds to a specific target section<br />
*** 5' fluorescent dye and 3' quencher<br />
*** No fluorescence when dye and quencher are close together<br />
*** During PCR, the extension of polymerase will cut the Taqman probe with an exonuclease, releasing the fluorescent probe<br />
*** As the probe is cut away from the quencher, a signal is released<br />
*** As amplification continues, more probes are separated from the quencher resulting in a larger signal<br />
** Get amplification curve over ~ 40 cycles<br />
*** Baseline phase (little fluorescent signal)<br />
*** Exponential phase as PCR product amplifies significantly ~ cycles 16-25<br />
*** Stationary phase once components are used up and no further amplification occurs<br />
** Threshold line is the point where there is a certain level of fluorescence above the background signal (set per instrument)<br />
** Cycle threshold (Ct) is the amount of cycles required to reach the threshold line<br />
*** If there's less target DNA/RNA present, it will take more cycles to amplify to this level = higher Ct<br />
*** If there's more target DNA/RNA present, it will take fewer cycles to reach this level = lower Ct<br />
*** Can use known standards to get absolute quantitation of target present by comparing the curves<br />
<br />
== MALDI-ToF ==<br />
Matrix-assisted laser desorption ionization time-of-flight<br />
<br />
* Laser vapourizes complex molecules into ionized protein molecules<br />
** Desorption removes molecules from sample<br />
** Ionization produces positively charged proteins that move through mass spec tube<br />
* Matrix (cinnamic acid) absorbs energy and protects sample<br />
* Measure mass-to-charge (m/z) ratio of molecules<br />
* Generates mass spectrum based on the flight time (speed) of the molecules = mass of ions<br />
** Smaller ions move faster<br />
* Compare results to database of known organisms</div>
Admin
https://medlabwiki.com/index.php?title=Microbiology_Quick_Reference&diff=205
Microbiology Quick Reference
2025-02-25T03:28:50Z
<p>Admin: /* Streptococcus species */</p>
<hr />
<div>== Microbiology Agars ==<br />
{| class="wikitable"<br />
|+<br />
!Agar<br />
!Enrichment<br />
!Selective<br />
!Differential Features<br />
!Use<br />
|-<br />
|Blood<br />
|5-10% sheep blood<br />
|<br />
|Shows hemolysis<br />
|General growth medium<br />
|-<br />
|Chocolate<br />
|5-10% lysed sheep blood<br />
2% hemoglobin + supplements<br />
|<br />
|<br />
|Growth of fastidious organisms<br />
|-<br />
|CNA<br />
|5-10% sheep blood<br />
|Gram positives grow<br />
<br />
* Colistin<br />
* Naladixic acid<br />
|Shows hemolysis<br />
|Growth of gram positives and yeast<br />
|-<br />
|MacConkey<br />
|<br />
|Gram negatives grow<br />
<br />
* Bile salts<br />
* Crystal violet<br />
|Shows lactose fermentation<br />
|Grow of gram negatives<br />
|}<br />
{| class="wikitable"<br />
!Agar<br />
!Features<br />
!Use<br />
|-<br />
|Meuller Hinton<br />
|<br />
|<br />
|-<br />
|MH + Sheep's blood<br />
|<br />
* Enrichment: sheep blood<br />
|AST for specific organisms<br />
<br />
* ''Streptococcus pneumoniae''<br />
|-<br />
|Thioglycollate broth<br />
|<br />
* Enrichment: hemin & vitamin K<br />
* Differential: O<sub>2</sub> use based on location of growth in tube<br />
|General growth medium, allows presumption of atmospheric growth conditions<br />
|-<br />
|Enrichment Media<br />
|<br />
* Usually broth<br />
* Grows fastidious or a specific organism from mixed specimens<br />
* Contain differential reagents to suppress normal flora for a short period of time<br />
** Requires subculture within ~ 12-18h<br />
|<br />
* Selenite broth<br />
* Tetrathionate broth<br />
* Brain-heart Infusion broth<br />
* Cooked meat broth<br />
|-<br />
|Sorbitol MacConkey<br />
|<br />
* Selective: for gram negatives<br />
* Differential: sorbitol fermentation<br />
|Enterohemorrhagic ''E. coli'' (non-sorbitol fermenters) vs other ''E. coli'' (sorbitol fermenters)<br />
|-<br />
|Salmonella-Shigella<br />
|<br />
* Selective: bile salts, sodium citrate, brilliant green<br />
** Selects for gram negative enteric pathogens<br />
* Differential: lactose fermentation + H<sub>2</sub>S production<br />
|Isolate enteric pathogens<br />
|-<br />
|Hektoen Agar<br />
|<br />
* Selective: bile salts<br />
** Selects for gram negative, mostly enteric pathogens<br />
* Differential: lactose, sucrose, and salicin fermentation + H<sub>2</sub>S production<br />
|Isolate enteric pathogens<br />
|-<br />
|Cefsulodin Irgasan Novobiocin (CIN)<br />
|<br />
* Selective: cefsulodin, irgasan, novobiocin, sodium desoxycholate, crystal violet<br />
** Inhibit gram + and normal stool flora<br />
* Differential: mannitol fermentation<br />
|Isolate ''Yersinia enterocolitica''<br />
|-<br />
|Campylobacter agar<br />
|<br />
* Enrichment: 10% sheep blood<br />
* Selective: <br />
** vancomycin (inhibit gram +)<br />
** amphotericin B + polymyxin B (inhibit yeast/fungus)<br />
** trimethoprim (prevent ''Proteus'' swarming)<br />
** cefoperazone (inhibit gram -)<br />
** Sodium bisulfite (creates microaerophillic environment)<br />
|Isolate ''Campylobacter''<br />
|-<br />
|<br />
|<br />
|<br />
|-<br />
|Mannitol salt agar<br />
|<br />
* Selective: 7.5% salt<br />
** Selects for halophiles<br />
* Differential: mannitol fermentation<br />
|Screen for ''Staphylococcus aureus''<br />
|-<br />
|New York City agar<br />
|<br />
* Enrichment: lysed blood, yeast dialysate, and plasma<br />
* Selective: vancomycin, colistin, amphotericin B, and trimethoprim <br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|}<br />
Chromogenic Agars<br />
<br />
Staphlyococcus aureus<br />
<br />
* MRSA Select agar<br />
* Denim blue agar<br />
<br />
Streptococcus agalactiae (Group B Strep)<br />
<br />
* Brilliance GBS agar<br />
<br />
== Specimen Collection ==<br />
Stool O&P<br />
<br />
* Unfixed<br />
* 10% formalin (general-purpose)<br />
* PVA polyvinyl alcohol (PCR and staining)<br />
* SAF sodium acetate-acetic acid-formalin (concentration and staining)<br />
GBS Screen<br />
<br />
* Vaginal-rectal swab<br />
* Todd-Hewitt broth with gentamicin and nalidixic acid to suppress other flora<br />
<br />
== Stains ==<br />
* Gram stain<br />
* Ziehl-Neelsen (acid fast)<br />
** Uses heat for uptake of carbolfuchsin<br />
* Kinyoun (acid fast)<br />
** Higher phenol concentration for uptake of carbolfuchsin<br />
* Auramine/Auramine-Rhodamine (acid fast)<br />
** fluorescent dye binds to mycolic acids<br />
* Acridine Orange (organisms without cell wall)<br />
** fluorescent dye binds to nucleic acid in cells<br />
** useful for organisms without cell wall (e.g., ''Mycoplasma'')<br />
* Calcofluor white (fungi)<br />
** Fluorescent dye binds to cellulose and chitin<br />
<br />
'''K'''inyoun = '''cold''', '''Acrid'''ine = nucleic '''acids''', '''C'''alcofluor = '''c'''hitin<br />
<br />
== Biochemical Tests ==<br />
{| class="wikitable"<br />
|+<br />
!Test<br />
!Purpose<br />
!Mechanism<br />
!Results<br />
|-<br />
|Hugh-Leifson Oxidation/Fermentation Test<br />
|Determines if organism can metabolize carbohydrates<br />
|Incubate tubes with 1% glucose + peptones<br />
Check for pH change in aerobic and anaerobic tubes<br />
<br />
* Fermenter: both +<br />
* Oxidizer: aerobic + only<br />
* Non-fermenter/oxidizer: both -<br />
|Positive: yellow<br />
Negative: green<br />
|-<br />
|ONPG<br />
|Differentiate late lactose fermenters from non-lactose fermenters<br />
<br />
* LLF: have β-galactosidase but not permease to allow cell uptake (may mutate or turn gene on after exposure to lactose)<br />
* NLF: no β-galactosidase (can't utilized lactose)<br />
|Use ONPG disk, which is similar to lactose but small enough to diffuse without permease<br />
|Positive LLF: any yellow<br />
Negative NLF: colourless<br />
|-<br />
|TSI (Triple Sugar Iron)<br />
|Detect fermentation of glucose, lactose, and/or sucrose<br />
Detect production of gases and H<sub>2</sub>S<br />
|0.1% glucose is used up first, then either:<br />
<br />
* Non-fermenters use peptones (alkaline in slant)<br />
* Fermenters use lactose and/or sucrose (acid in both butt and slant)<br />
|Glucose only: NA/A (pink slant, yellow butt)<br />
Multiple carbohydrates: A/A (yellow slant and butt)<br />
Aerobic organism (no fermentation): NA/NC (red slant and butt)<br />
May also produce gas and/or H<sub>2</sub>S<br />
|-<br />
|MRVP<br />
|Used to determine type of pyruvate fermentation pathway used<br />
<br />
* MR uses mixed-acid pathway<br />
* VP uses 2,3-butanediol pathway<br />
|Mixed acid fermentation produces acid end-products (lactic acid and acetic acid), causing pH change<br />
2,3-butanediol pathway produces acetoin<br />
|<br />
|-<br />
|Decarboxylation<br />
|<br />
|<br />
|<br />
|-<br />
|Arginine Dihydrolase<br />
|<br />
|<br />
|<br />
|-<br />
|Phenylalanine Deaminase (PPD)<br />
|Used to test for phenylalanine deaminase<br />
<br />
* Present in gram negative bacilli<br />
|<br />
|Positive: green<br />
Negative: yellow<br />
|-<br />
|Simmon's Citrate<br />
|<br />
|<br />
|Positive: blue or green with growth<br />
Negative: green, no growth<br />
|-<br />
|Gelatin test<br />
|<br />
|<br />
|<br />
|-<br />
|Indole<br />
|<br />
|<br />
|<br />
|-<br />
|Sulfide-Indole-Motility (SIM)<br />
|<br />
|<br />
|<br />
|-<br />
|Nitrate Test<br />
|Determines whether organism has nitrate reductase to produce O<sub>2</sub> anaerobically<br />
|Nitrate reductase converts nitrate -> nitrite (NO<sub>2</sub>)<br />
Some organisms further break down nitrite to nitrogen gas<br />
|If red at first tube = nitrites positive<br />
If not red, then but add zinc<br />
<br />
* Red = negative (original nitrates present)<br />
* No colour = positive (nitrite reduced to N2)<br />
|-<br />
|Urea Test<br />
|<br />
|<br />
|<br />
|}<br />
<br />
== Organism Testing ==<br />
{| class="wikitable"<br />
|+<br />
!Test<br />
!Positive QC<br />
!Negative QC<br />
!Uses<br />
|-<br />
|Catalase<br />
|''Staphylococcus spp.''<br />
|<br />
|<br />
|-<br />
|Coagulase<br />
| rowspan="2" |''S. aureus''<br />
| rowspan="2" |Other ''Staphylococcus''<br />
|<br />
|-<br />
|Staphaureux (Latex agglutination)<br />
|<br />
|-<br />
|PYR<br />
|''S. lugdunensis''<br />
|<br />
|<br />
|}<br />
<br />
==== ''Staphylococcus'' species ====<br />
''Staphylococcus aureus''<br />
<br />
* GPC clusters<br />
* Catalase +<br />
* Tube Coagulase + (forms clot in plasma due to Staphylocoagulase)<br />
* Staphaureux +<br />
<br />
If coagulase/Staphaureux negative, then CoNS:<br />
<br />
* ''S. lugdunensis'': PYR +, ORN +<br />
** Has clumping factor that '''can cause weak false positives'''!<br />
* ''S. saprophyticus'' (females 12-60): Novobiocin resistant (≤16 mm)<br />
* Others: ''S. epidermidis'', ''S. hominis'', other CoNS<br />
Related Species (''Micrococcus, Stomatococcus, Planococcus'')<br />
<br />
* Often normal flora<br />
* Similar test results to ''Staphylococcus'' spp.<br />
<br />
==== ''Streptococcus'' species ====<br />
<br />
* GPC pairs & chains<br />
* Catalase -<br />
<br />
Lancefield grouping mainly used for ID<br />
{| class="wikitable"<br />
|+<br />
!Lancefield Grouping<br />
!Organism<br />
!Features<br />
!Clinical Relevance<br />
|-<br />
|Group A<br />
|''S. pyogenes''<br />
|<br />
* Beta-heme (large zone)<br />
* PYR +<br />
* Bacitracin S<br />
* Hippurate hydrolysis neg<br />
|iGAS<br />
|-<br />
|Group B<br />
|''S. agalactiae''<br />
|<br />
* Beta-heme (narrow zone)<br />
* Hippurate +<br />
* Bacitracin R<br />
* CAMP test + (enhanced hemolysis when near beta-heme ''S. aureus'')<br />
|Neonatal infections<br />
|-<br />
| rowspan="2" |Group D<br />
|''S. bovis''<br />
|<br />
* Non-heme<br />
* '''PYR -'''<br />
* '''Bile esculin +'''<br />
|<br />
* Sepsis, sub-acute endocarditis, meningitis<br />
* UTIs<br />
* Association with GI carcinomas<br />
|-<br />
|Enterococcus<br />
<br />
* '''''E. faecalis''''' '''(most common)'''<br />
* '''''E. faecium'' (majority of VREs)'''<br />
* ''E. gallinarum''<br />
* ''E. casseliflavus''<br /><br />
|<br />
* Non-heme, possibly very small beta-heme on some media<br />
* '''PYR +'''<br />
* '''Bile esculin +'''<br />
|<br />
|-<br />
|Group C<br />
| rowspan="2" |''Streptococcus dysgalactiae'' subsp ''equisimilis''<br />
| rowspan="2" |Beta-heme (large zone)<br />
| rowspan="2" |Normally commensal<br />
Possibly cause pharyngitis<br />
|-<br />
|Group G<br />
|-<br />
|Non-groupable<br />
|''S. pneumoniae''<br />
|<br />
* Alpha-heme<br />
* "Checkerboard" colonial appearance<br />
* Bile soluble<br />
* Optochin sensitive (≥14mm)<br />
|<br />
* Otitis media<br />
* Sinusitis<br />
* Pneumonia<br />
* Meningitis<br />
* Etc.<br />
|-<br />
|Various/non-groupable<br />
|Viridans Streptococci<br />
<br />
* ''S. mitis'', ''S. mutans, S. salivarius, S. bovis, S. anginosus''<br />
|<br />
* Most alpha-heme, but also beta- and non-heme<br />
*<br />
|<br />
|}<br />
''Enterococcus'' sp.<br />
<br />
Organisms of infection control concern<br />
<br />
''E. faecalis''<br />
<br />
* PYR +<br />
* Bile esculin +<br />
* Arabinose -<br />
* MGP -<br />
<br />
''E. faecium''<br />
<br />
* PYR +<br />
* Bile esculin +<br />
* Arabinose +<br />
* MGP -<br />
<br />
Other ''Enterococci'' (no infection control concern)<br />
<br />
''E. gallinarum''<br />
<br />
* MGP +<br />
<br />
''E. casseliflavus''<br />
<br />
Catalase<br />
<br />
Oxidase<br />
<br />
PYR<br />
<br />
== Antibiotic Susceptibility Testing ==<br />
MRSA<br />
<br />
* Penicillins bind to PBP (penicillin binding protein) = inhibits cell wall formation<br />
* MRSAs have mecA gene encoding PBP2a<br />
** PBP2a resistant to ALL beta-lactams<br />
*Test using oxacillin screen and Kirby-Bauer (cefoxitin)<br />
<br />
BORSA (Borderline Oxacillin Resistant ''Staphylococcus aureus'')<br />
<br />
* '''NOT''' due to mecA (therefore, have altered PBP but '''NOT''' PBP2a)<br />
* Due to superproduction of beta-lactamase<br />
* MIC above oxacillin breakpoints (>4 μg/mL), but don't grow on oxacillin screen plates<br />
<br />
VISA<br />
<br />
* Vancomycin MIC breakpoint 4-8 μg/mL<br />
* Possibly due to thickened cell wall, trapping antibiotic<br />
* Test using vancomycin screen<br />
<br />
VRSA<br />
<br />
* Vancomycin MIC breakpoint >8 μg/mL<br />
* vanA resistance from plasmids or transposons (e.g., from VREs)<br />
* Test using vancomycin screen<br />
VRE<br />
<br />
* vanA or vanB associated with outbreaks ''(E. faecalis'' and ''E. faecium'')<br />
* vanC intrinsic - not associated with outbreaks (''E. gallinarum'' and ''E. casseliflavus'')<br />
<br />
D-Test<br />
<br />
* Test for inducible clindamycin resistance<br />
** Presence of ''erm'' gene<br />
** Causes flattening of zone<br />
<br />
== Mycology ==<br />
* Malassezia furfur = Tinea versicolour = budding yeast and hyphae in 10% KOH ("spaghetti and meatballs")<br />
* Candida albicans = polymorphic, chlamydospore +, germ tube +, urea -<br />
* Candida auris = germ tube -<br />
* Cryptococcus = germ tube -, india ink +, urea +<br />
<br />
== Parasitology ==<br />
* Definitive/true host = where parasite develops into sexually mature (adult) form<br />
* Intermediate/secondary host = in-between host where parasite is sexually immature (e.g., larvae)<br />
* Entamoeba histolytica = spoke-like central karyosome(s)<br />
* Trichomonas vaginalis = one nuclei (often oval and to one side), flagella<br />
* Balantidium coli = large, ciliated<br />
* Schistosoma = egg with prominent spine/spike<br />
* Enterobius vermicularis = pinworm, egg is elongated oval with one side flattened<br />
* Strongyloides = larvae migrating through agar<br />
<br />
== Polymerase Chain Reaction ==<br />
<br />
* Taq polymerase used along with dNTPs (nucleotides for elongation), and primers (DNA or RNA sequence of interest)<br />
* Buffer pH at 8.0-9.5, include salts MgCl<sub>2</sub> and KCl<br />
* Amplified through multiple cycles (usually 25-30)<br />
* 95C denature - 60C anneal - 72C extend<br />
* qPCR provides amplification and detection together<br />
** detect products as they're produced<br />
** use fluorescent dye<br />
*** SYBR green or Taqman probe<br />
** SYBR green binds to any double-stranded DNA and fluoresces (more DNA produced = more fluorescence)<br />
** Taqman is more specific, and binds to a specific target section<br />
*** 5' fluorescent dye and 3' quencher<br />
*** No fluorescence when dye and quencher are close together<br />
*** During PCR, the extension of polymerase will cut the Taqman probe with an exonuclease, releasing the fluorescent probe<br />
*** As the probe is cut away from the quencher, a signal is released<br />
*** As amplification continues, more probes are separated from the quencher resulting in a larger signal<br />
** Get amplification curve over ~ 40 cycles<br />
*** Baseline phase (little fluorescent signal)<br />
*** Exponential phase as PCR product amplifies significantly ~ cycles 16-25<br />
*** Stationary phase once components are used up and no further amplification occurs<br />
** Threshold line is the point where there is a certain level of fluorescence above the background signal (set per instrument)<br />
** Cycle threshold (Ct) is the amount of cycles required to reach the threshold line<br />
*** If there's less target DNA/RNA present, it will take more cycles to amplify to this level = higher Ct<br />
*** If there's more target DNA/RNA present, it will take fewer cycles to reach this level = lower Ct<br />
*** Can use known standards to get absolute quantitation of target present by comparing the curves<br />
<br />
== MALDI-ToF ==<br />
Matrix-assisted laser desorption ionization time-of-flight<br />
<br />
* Laser vapourizes complex molecules into ionized protein molecules<br />
** Desorption removes molecules from sample<br />
** Ionization produces positively charged proteins that move through mass spec tube<br />
* Matrix (cinnamic acid) absorbs energy and protects sample<br />
* Measure mass-to-charge (m/z) ratio of molecules<br />
* Generates mass spectrum based on the flight time (speed) of the molecules = mass of ions<br />
** Smaller ions move faster<br />
* Compare results to database of known organisms</div>
Admin
https://medlabwiki.com/index.php?title=Microbiology_Quick_Reference&diff=204
Microbiology Quick Reference
2025-02-25T00:50:01Z
<p>Admin: /* Specimen Collection */</p>
<hr />
<div>== Microbiology Agars ==<br />
{| class="wikitable"<br />
|+<br />
!Agar<br />
!Enrichment<br />
!Selective<br />
!Differential Features<br />
!Use<br />
|-<br />
|Blood<br />
|5-10% sheep blood<br />
|<br />
|Shows hemolysis<br />
|General growth medium<br />
|-<br />
|Chocolate<br />
|5-10% lysed sheep blood<br />
2% hemoglobin + supplements<br />
|<br />
|<br />
|Growth of fastidious organisms<br />
|-<br />
|CNA<br />
|5-10% sheep blood<br />
|Gram positives grow<br />
<br />
* Colistin<br />
* Naladixic acid<br />
|Shows hemolysis<br />
|Growth of gram positives and yeast<br />
|-<br />
|MacConkey<br />
|<br />
|Gram negatives grow<br />
<br />
* Bile salts<br />
* Crystal violet<br />
|Shows lactose fermentation<br />
|Grow of gram negatives<br />
|}<br />
{| class="wikitable"<br />
!Agar<br />
!Features<br />
!Use<br />
|-<br />
|Meuller Hinton<br />
|<br />
|<br />
|-<br />
|MH + Sheep's blood<br />
|<br />
* Enrichment: sheep blood<br />
|AST for specific organisms<br />
<br />
* ''Streptococcus pneumoniae''<br />
|-<br />
|Thioglycollate broth<br />
|<br />
* Enrichment: hemin & vitamin K<br />
* Differential: O<sub>2</sub> use based on location of growth in tube<br />
|General growth medium, allows presumption of atmospheric growth conditions<br />
|-<br />
|Enrichment Media<br />
|<br />
* Usually broth<br />
* Grows fastidious or a specific organism from mixed specimens<br />
* Contain differential reagents to suppress normal flora for a short period of time<br />
** Requires subculture within ~ 12-18h<br />
|<br />
* Selenite broth<br />
* Tetrathionate broth<br />
* Brain-heart Infusion broth<br />
* Cooked meat broth<br />
|-<br />
|Sorbitol MacConkey<br />
|<br />
* Selective: for gram negatives<br />
* Differential: sorbitol fermentation<br />
|Enterohemorrhagic ''E. coli'' (non-sorbitol fermenters) vs other ''E. coli'' (sorbitol fermenters)<br />
|-<br />
|Salmonella-Shigella<br />
|<br />
* Selective: bile salts, sodium citrate, brilliant green<br />
** Selects for gram negative enteric pathogens<br />
* Differential: lactose fermentation + H<sub>2</sub>S production<br />
|Isolate enteric pathogens<br />
|-<br />
|Hektoen Agar<br />
|<br />
* Selective: bile salts<br />
** Selects for gram negative, mostly enteric pathogens<br />
* Differential: lactose, sucrose, and salicin fermentation + H<sub>2</sub>S production<br />
|Isolate enteric pathogens<br />
|-<br />
|Cefsulodin Irgasan Novobiocin (CIN)<br />
|<br />
* Selective: cefsulodin, irgasan, novobiocin, sodium desoxycholate, crystal violet<br />
** Inhibit gram + and normal stool flora<br />
* Differential: mannitol fermentation<br />
|Isolate ''Yersinia enterocolitica''<br />
|-<br />
|Campylobacter agar<br />
|<br />
* Enrichment: 10% sheep blood<br />
* Selective: <br />
** vancomycin (inhibit gram +)<br />
** amphotericin B + polymyxin B (inhibit yeast/fungus)<br />
** trimethoprim (prevent ''Proteus'' swarming)<br />
** cefoperazone (inhibit gram -)<br />
** Sodium bisulfite (creates microaerophillic environment)<br />
|Isolate ''Campylobacter''<br />
|-<br />
|<br />
|<br />
|<br />
|-<br />
|Mannitol salt agar<br />
|<br />
* Selective: 7.5% salt<br />
** Selects for halophiles<br />
* Differential: mannitol fermentation<br />
|Screen for ''Staphylococcus aureus''<br />
|-<br />
|New York City agar<br />
|<br />
* Enrichment: lysed blood, yeast dialysate, and plasma<br />
* Selective: vancomycin, colistin, amphotericin B, and trimethoprim <br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|}<br />
<br />
== Specimen Collection ==<br />
Stool O&P<br />
<br />
* Unfixed<br />
* 10% formalin (general-purpose)<br />
* PVA polyvinyl alcohol (PCR and staining)<br />
* SAF sodium acetate-acetic acid-formalin (concentration and staining)<br />
<br />
== Stains ==<br />
* Gram stain<br />
* Ziehl-Neelsen (acid fast)<br />
** Uses heat for uptake of carbolfuchsin<br />
* Kinyoun (acid fast)<br />
** Higher phenol concentration for uptake of carbolfuchsin<br />
* Auramine/Auramine-Rhodamine (acid fast)<br />
** fluorescent dye binds to mycolic acids<br />
* Acridine Orange (organisms without cell wall)<br />
** fluorescent dye binds to nucleic acid in cells<br />
** useful for organisms without cell wall (e.g., ''Mycoplasma'')<br />
* Calcofluor white (fungi)<br />
** Fluorescent dye binds to cellulose and chitin<br />
<br />
'''K'''inyoun = '''cold''', '''Acrid'''ine = nucleic '''acids''', '''C'''alcofluor = '''c'''hitin<br />
<br />
== Biochemical Tests ==<br />
{| class="wikitable"<br />
|+<br />
!Test<br />
!Purpose<br />
!Mechanism<br />
!Results<br />
|-<br />
|Hugh-Leifson Oxidation/Fermentation Test<br />
|Determines if organism can metabolize carbohydrates<br />
|Incubate tubes with 1% glucose + peptones<br />
Check for pH change in aerobic and anaerobic tubes<br />
<br />
* Fermenter: both +<br />
* Oxidizer: aerobic + only<br />
* Non-fermenter/oxidizer: both -<br />
|Positive: yellow<br />
Negative: green<br />
|-<br />
|ONPG<br />
|Differentiate late lactose fermenters from non-lactose fermenters<br />
<br />
* LLF: have β-galactosidase but not permease to allow cell uptake (may mutate or turn gene on after exposure to lactose)<br />
* NLF: no β-galactosidase (can't utilized lactose)<br />
|Use ONPG disk, which is similar to lactose but small enough to diffuse without permease<br />
|Positive LLF: any yellow<br />
Negative NLF: colourless<br />
|-<br />
|TSI (Triple Sugar Iron)<br />
|Detect fermentation of glucose, lactose, and/or sucrose<br />
Detect production of gases and H<sub>2</sub>S<br />
|0.1% glucose is used up first, then either:<br />
<br />
* Non-fermenters use peptones (alkaline in slant)<br />
* Fermenters use lactose and/or sucrose (acid in both butt and slant)<br />
|Glucose only: NA/A (pink slant, yellow butt)<br />
Multiple carbohydrates: A/A (yellow slant and butt)<br />
Aerobic organism (no fermentation): NA/NC (red slant and butt)<br />
May also produce gas and/or H<sub>2</sub>S<br />
|-<br />
|MRVP<br />
|Used to determine type of pyruvate fermentation pathway used<br />
<br />
* MR uses mixed-acid pathway<br />
* VP uses 2,3-butanediol pathway<br />
|Mixed acid fermentation produces acid end-products (lactic acid and acetic acid), causing pH change<br />
2,3-butanediol pathway produces acetoin<br />
|<br />
|-<br />
|Decarboxylation<br />
|<br />
|<br />
|<br />
|-<br />
|Arginine Dihydrolase<br />
|<br />
|<br />
|<br />
|-<br />
|Phenylalanine Deaminase (PPD)<br />
|Used to test for phenylalanine deaminase<br />
<br />
* Present in gram negative bacilli<br />
|<br />
|Positive: green<br />
Negative: yellow<br />
|-<br />
|Simmon's Citrate<br />
|<br />
|<br />
|Positive: blue or green with growth<br />
Negative: green, no growth<br />
|-<br />
|Gelatin test<br />
|<br />
|<br />
|<br />
|-<br />
|Indole<br />
|<br />
|<br />
|<br />
|-<br />
|Sulfide-Indole-Motility (SIM)<br />
|<br />
|<br />
|<br />
|-<br />
|Nitrate Test<br />
|Determines whether organism has nitrate reductase to produce O<sub>2</sub> anaerobically<br />
|Nitrate reductase converts nitrate -> nitrite (NO<sub>2</sub>)<br />
Some organisms further break down nitrite to nitrogen gas<br />
|If red at first tube = nitrites positive<br />
If not red, then but add zinc<br />
<br />
* Red = negative (original nitrates present)<br />
* No colour = positive (nitrite reduced to N2)<br />
|-<br />
|Urea Test<br />
|<br />
|<br />
|<br />
|}<br />
<br />
== Organism Testing ==<br />
{| class="wikitable"<br />
|+<br />
!Test<br />
!Positive QC<br />
!Negative QC<br />
!Uses<br />
|-<br />
|Catalase<br />
|''Staphylococcus spp.''<br />
|<br />
|<br />
|-<br />
|Coagulase<br />
| rowspan="2" |''S. aureus''<br />
| rowspan="2" |Other ''Staphylococcus''<br />
|<br />
|-<br />
|Staphaureux (Latex agglutination)<br />
|<br />
|-<br />
|PYR<br />
|''S. lugdunensis''<br />
|<br />
|<br />
|}<br />
<br />
==== ''Staphylococcus'' species ====<br />
''Staphylococcus aureus''<br />
<br />
* GPC clusters<br />
* Catalase +<br />
* Coagulase + (forms clot in plasma due to Staphylocoagulase)<br />
* Staphaureux +<br />
<br />
If coagulase/Staphaureux negative, then CoNS:<br />
<br />
* ''S. lugdunensis'': PYR +<br />
** Has clumping factor that '''can cause weak false positives'''!<br />
* ''S. saprophyticus'' (females 12-60): Novobiocin resistant<br />
* Others: ''S. epidermidis'', ''S. hominis'', other CoNS<br />
Related Species (''Micrococcus, Stomatococcus, Planococcus'')<br />
<br />
* Often normal flora<br />
* Similar test results to ''Staphylococcus'' spp.<br />
<br />
==== ''Streptococcus'' species ====<br />
<br />
* GPC pairs & chains<br />
* Catalase -<br />
<br />
Lancefield grouping mainly used for ID<br />
{| class="wikitable"<br />
|+<br />
!Lancefield Grouping<br />
!Organism<br />
!Features<br />
!Clinical Relevance<br />
|-<br />
|Group A<br />
|''S. pyogenes''<br />
|<br />
* Beta-heme<br />
* PYR +<br />
|iGAS<br />
|-<br />
|Group B<br />
|''S. agalactiae''<br />
|<br />
* Beta-heme<br />
|<br />
|-<br />
| rowspan="2" |Group D<br />
|''S. bovis''<br />
|<br />
|<br />
|-<br />
|Enterococcus<br />
<br />
<br />
|<br />
|<br />
|-<br />
|Group C<br />
| rowspan="2" |''Streptococcus dysgalactiae'' subsp ''equisimilis''<br />
| rowspan="2" |Beta-heme<br />
| rowspan="2" |Normally commensal<br />
|-<br />
|Group G<br />
|-<br />
|<br />
|''S. pneumoniae''<br />
|<br />
* Alpha-heme<br />
* Bile soluble<br />
* Optochin sensitive (≥14mm)<br />
|<br />
|-<br />
|<br />
|Viridans Streptococci<br />
|<br />
|<br />
|}<br />
Catalase<br />
<br />
Oxidase<br />
<br />
PYR<br />
<br />
== Antibiotic Susceptibility Testing ==<br />
MRSA<br />
<br />
* Penicillins bind to PBP (penicillin binding protein) = inhibits cell wall formation<br />
* MRSAs have mecA gene encoding PBP2a<br />
** PBP2a resistant to ALL beta-lactams<br />
<br />
BORSA (Borderline Oxacillin Resistant ''Staphylococcus aureus'')<br />
<br />
* '''NOT''' due to mecA (therefore, have altered PBP but '''NOT''' PBP2a)<br />
* Due to superproduction of beta-lactamase<br />
* MIC above oxacillin breakpoints (>4 μg/mL), but don't grow on oxacillin screen plates<br />
<br />
VISA<br />
<br />
* Vancomycin MIC breakpoint 4-8 μg/mL<br />
* Possibly due to thickened cell wall, trapping antibiotic<br />
<br />
VRSA<br />
<br />
* Vancomycin MIC breakpoint >8 μg/mL<br />
* vanA resistance from plasmids or transposons (e.g., from VREs)<br />
<br />
== Mycology ==<br />
* Malassezia furfur = Tinea versicolour = budding yeast and hyphae in 10% KOH ("spaghetti and meatballs")<br />
* Candida albicans = polymorphic, chlamydospore +, germ tube +, urea -<br />
* Candida auris = germ tube -<br />
* Cryptococcus = germ tube -, india ink +, urea +<br />
<br />
== Parasitology ==<br />
* Definitive/true host = where parasite develops into sexually mature (adult) form<br />
* Intermediate/secondary host = in-between host where parasite is sexually immature (e.g., larvae)<br />
* Entamoeba histolytica = spoke-like central karyosome(s)<br />
* Trichomonas vaginalis = one nuclei (often oval and to one side), flagella<br />
* Balantidium coli = large, ciliated<br />
* Schistosoma = egg with prominent spine/spike<br />
* Enterobius vermicularis = pinworm, egg is elongated oval with one side flattened<br />
* Strongyloides = larvae migrating through agar<br />
<br />
== Polymerase Chain Reaction ==<br />
<br />
* Taq polymerase used along with dNTPs (nucleotides for elongation), and primers (DNA or RNA sequence of interest)<br />
* Buffer pH at 8.0-9.5, include salts MgCl<sub>2</sub> and KCl<br />
* Amplified through multiple cycles (usually 25-30)<br />
* 95C denature - 60C anneal - 72C extend<br />
* qPCR provides amplification and detection together<br />
** detect products as they're produced<br />
** use fluorescent dye<br />
*** SYBR green or Taqman probe<br />
** SYBR green binds to any double-stranded DNA and fluoresces (more DNA produced = more fluorescence)<br />
** Taqman is more specific, and binds to a specific target section<br />
*** 5' fluorescent dye and 3' quencher<br />
*** No fluorescence when dye and quencher are close together<br />
*** During PCR, the extension of polymerase will cut the Taqman probe with an exonuclease, releasing the fluorescent probe<br />
*** As the probe is cut away from the quencher, a signal is released<br />
*** As amplification continues, more probes are separated from the quencher resulting in a larger signal<br />
** Get amplification curve over ~ 40 cycles<br />
*** Baseline phase (little fluorescent signal)<br />
*** Exponential phase as PCR product amplifies significantly ~ cycles 16-25<br />
*** Stationary phase once components are used up and no further amplification occurs<br />
** Threshold line is the point where there is a certain level of fluorescence above the background signal (set per instrument)<br />
** Cycle threshold (Ct) is the amount of cycles required to reach the threshold line<br />
*** If there's less target DNA/RNA present, it will take more cycles to amplify to this level = higher Ct<br />
*** If there's more target DNA/RNA present, it will take fewer cycles to reach this level = lower Ct<br />
*** Can use known standards to get absolute quantitation of target present by comparing the curves<br />
<br />
== MALDI-ToF ==<br />
Matrix-assisted laser desorption ionization time-of-flight<br />
<br />
* Laser vapourizes complex molecules into ionized protein molecules<br />
** Desorption removes molecules from sample<br />
** Ionization produces positively charged proteins that move through mass spec tube<br />
* Matrix (cinnamic acid) absorbs energy and protects sample<br />
* Measure mass-to-charge (m/z) ratio of molecules<br />
* Generates mass spectrum based on the flight time (speed) of the molecules = mass of ions<br />
** Smaller ions move faster<br />
* Compare results to database of known organisms</div>
Admin
https://medlabwiki.com/index.php?title=Microbiology_Quick_Reference&diff=203
Microbiology Quick Reference
2025-02-22T05:36:35Z
<p>Admin: /* Streptococcus species */</p>
<hr />
<div>== Microbiology Agars ==<br />
{| class="wikitable"<br />
|+<br />
!Agar<br />
!Enrichment<br />
!Selective<br />
!Differential Features<br />
!Use<br />
|-<br />
|Blood<br />
|5-10% sheep blood<br />
|<br />
|Shows hemolysis<br />
|General growth medium<br />
|-<br />
|Chocolate<br />
|5-10% lysed sheep blood<br />
2% hemoglobin + supplements<br />
|<br />
|<br />
|Growth of fastidious organisms<br />
|-<br />
|CNA<br />
|5-10% sheep blood<br />
|Gram positives grow<br />
<br />
* Colistin<br />
* Naladixic acid<br />
|Shows hemolysis<br />
|Growth of gram positives and yeast<br />
|-<br />
|MacConkey<br />
|<br />
|Gram negatives grow<br />
<br />
* Bile salts<br />
* Crystal violet<br />
|Shows lactose fermentation<br />
|Grow of gram negatives<br />
|}<br />
{| class="wikitable"<br />
!Agar<br />
!Features<br />
!Use<br />
|-<br />
|Meuller Hinton<br />
|<br />
|<br />
|-<br />
|MH + Sheep's blood<br />
|<br />
* Enrichment: sheep blood<br />
|AST for specific organisms<br />
<br />
* ''Streptococcus pneumoniae''<br />
|-<br />
|Thioglycollate broth<br />
|<br />
* Enrichment: hemin & vitamin K<br />
* Differential: O<sub>2</sub> use based on location of growth in tube<br />
|General growth medium, allows presumption of atmospheric growth conditions<br />
|-<br />
|Enrichment Media<br />
|<br />
* Usually broth<br />
* Grows fastidious or a specific organism from mixed specimens<br />
* Contain differential reagents to suppress normal flora for a short period of time<br />
** Requires subculture within ~ 12-18h<br />
|<br />
* Selenite broth<br />
* Tetrathionate broth<br />
* Brain-heart Infusion broth<br />
* Cooked meat broth<br />
|-<br />
|Sorbitol MacConkey<br />
|<br />
* Selective: for gram negatives<br />
* Differential: sorbitol fermentation<br />
|Enterohemorrhagic ''E. coli'' (non-sorbitol fermenters) vs other ''E. coli'' (sorbitol fermenters)<br />
|-<br />
|Salmonella-Shigella<br />
|<br />
* Selective: bile salts, sodium citrate, brilliant green<br />
** Selects for gram negative enteric pathogens<br />
* Differential: lactose fermentation + H<sub>2</sub>S production<br />
|Isolate enteric pathogens<br />
|-<br />
|Hektoen Agar<br />
|<br />
* Selective: bile salts<br />
** Selects for gram negative, mostly enteric pathogens<br />
* Differential: lactose, sucrose, and salicin fermentation + H<sub>2</sub>S production<br />
|Isolate enteric pathogens<br />
|-<br />
|Cefsulodin Irgasan Novobiocin (CIN)<br />
|<br />
* Selective: cefsulodin, irgasan, novobiocin, sodium desoxycholate, crystal violet<br />
** Inhibit gram + and normal stool flora<br />
* Differential: mannitol fermentation<br />
|Isolate ''Yersinia enterocolitica''<br />
|-<br />
|Campylobacter agar<br />
|<br />
* Enrichment: 10% sheep blood<br />
* Selective: <br />
** vancomycin (inhibit gram +)<br />
** amphotericin B + polymyxin B (inhibit yeast/fungus)<br />
** trimethoprim (prevent ''Proteus'' swarming)<br />
** cefoperazone (inhibit gram -)<br />
** Sodium bisulfite (creates microaerophillic environment)<br />
|Isolate ''Campylobacter''<br />
|-<br />
|<br />
|<br />
|<br />
|-<br />
|Mannitol salt agar<br />
|<br />
* Selective: 7.5% salt<br />
** Selects for halophiles<br />
* Differential: mannitol fermentation<br />
|Screen for ''Staphylococcus aureus''<br />
|-<br />
|New York City agar<br />
|<br />
* Enrichment: lysed blood, yeast dialysate, and plasma<br />
* Selective: vancomycin, colistin, amphotericin B, and trimethoprim <br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|}<br />
<br />
== Specimen Collection ==<br />
Stool O&P<br />
<br />
* Unfixed<br />
* 10% formalin (general-purpose)<br />
* PVA polyvinyl alcohol (PCR and staining)<br />
* SAF sodium acetate-acetic acid-formalin (concentration and staining)<br />
<br />
== Stains ==<br />
* Gram stain<br />
* Ziehl-Neelsen (acid fast)<br />
** Uses heat for uptake of carbolfuchsin<br />
* Kinyoun (acid fast)<br />
** Higher phenol concentration for uptake of carbolfuchsin<br />
* Auramine/Auramine-Rhodamine (acid fast)<br />
** fluorescent dye binds to mycolic acids<br />
* Acridine Orange (organisms without cell wall)<br />
** fluorescent dye binds to nucleic acid in cells<br />
** useful for organisms without cell wall (e.g., ''Mycoplasma'')<br />
* Calcofluor white (fungi)<br />
** Fluorescent dye binds to cellulose and chitin<br />
<br />
'''K'''inyoun = '''cold''', '''Acrid'''ine = nucleic '''acids''', '''C'''alcofluor = '''c'''hitin<br />
<br />
== Biochemical Tests ==<br />
{| class="wikitable"<br />
|+<br />
!Test<br />
!Purpose<br />
!Mechanism<br />
!Results<br />
|-<br />
|Hugh-Leifson Oxidation/Fermentation Test<br />
|Determines if organism can metabolize carbohydrates<br />
|Incubate tubes with 1% glucose + peptones<br />
Check for pH change in aerobic and anaerobic tubes<br />
<br />
* Fermenter: both +<br />
* Oxidizer: aerobic + only<br />
* Non-fermenter/oxidizer: both -<br />
|Positive: yellow<br />
Negative: green<br />
|-<br />
|ONPG<br />
|Differentiate late lactose fermenters from non-lactose fermenters<br />
<br />
* LLF: have β-galactosidase but not permease to allow cell uptake (may mutate or turn gene on after exposure to lactose)<br />
* NLF: no β-galactosidase (can't utilized lactose)<br />
|Use ONPG disk, which is similar to lactose but small enough to diffuse without permease<br />
|Positive LLF: any yellow<br />
Negative NLF: colourless<br />
|-<br />
|TSI (Triple Sugar Iron)<br />
|Detect fermentation of glucose, lactose, and/or sucrose<br />
Detect production of gases and H<sub>2</sub>S<br />
|0.1% glucose is used up first, then either:<br />
<br />
* Non-fermenters use peptones (alkaline in slant)<br />
* Fermenters use lactose and/or sucrose (acid in both butt and slant)<br />
|Glucose only: NA/A (pink slant, yellow butt)<br />
Multiple carbohydrates: A/A (yellow slant and butt)<br />
Aerobic organism (no fermentation): NA/NC (red slant and butt)<br />
May also produce gas and/or H<sub>2</sub>S<br />
|-<br />
|MRVP<br />
|Used to determine type of pyruvate fermentation pathway used<br />
<br />
* MR uses mixed-acid pathway<br />
* VP uses 2,3-butanediol pathway<br />
|Mixed acid fermentation produces acid end-products (lactic acid and acetic acid), causing pH change<br />
2,3-butanediol pathway produces acetoin<br />
|<br />
|-<br />
|Decarboxylation<br />
|<br />
|<br />
|<br />
|-<br />
|Arginine Dihydrolase<br />
|<br />
|<br />
|<br />
|-<br />
|Phenylalanine Deaminase (PPD)<br />
|Used to test for phenylalanine deaminase<br />
<br />
* Present in gram negative bacilli<br />
|<br />
|Positive: green<br />
Negative: yellow<br />
|-<br />
|Simmon's Citrate<br />
|<br />
|<br />
|Positive: blue or green with growth<br />
Negative: green, no growth<br />
|-<br />
|Gelatin test<br />
|<br />
|<br />
|<br />
|-<br />
|Indole<br />
|<br />
|<br />
|<br />
|-<br />
|Sulfide-Indole-Motility (SIM)<br />
|<br />
|<br />
|<br />
|-<br />
|Nitrate Test<br />
|Determines whether organism has nitrate reductase to produce O<sub>2</sub> anaerobically<br />
|Nitrate reductase converts nitrate -> nitrite (NO<sub>2</sub>)<br />
Some organisms further break down nitrite to nitrogen gas<br />
|If red at first tube = nitrites positive<br />
If not red, then but add zinc<br />
<br />
* Red = negative (original nitrates present)<br />
* No colour = positive (nitrite reduced to N2)<br />
|-<br />
|Urea Test<br />
|<br />
|<br />
|<br />
|}<br />
{| class="wikitable"<br />
|+<br />
!Test<br />
!Positive QC<br />
!Negative QC<br />
!Uses<br />
|-<br />
|Catalase<br />
|''Staphylococcus spp.''<br />
|<br />
|<br />
|-<br />
|Coagulase<br />
| rowspan="2" |''S. aureus''<br />
| rowspan="2" |Other ''Staphylococcus''<br />
|<br />
|-<br />
|Staphaureux (Latex agglutination)<br />
|<br />
|-<br />
|PYR<br />
|''S. lugdunensis''<br />
|<br />
|<br />
|}<br />
<br />
==== ''Staphylococcus'' species ====<br />
''Staphylococcus aureus''<br />
<br />
* GPC clusters<br />
* Catalase +<br />
* Coagulase +<br />
* Staphaureux +<br />
<br />
If coagulase/Staphaureux negative, then CoNS:<br />
<br />
* ''S. lugdunensis'': PYR +<br />
* ''S. saprophyticus'' (females 12-60): Novobiocin resistant<br />
* Others: ''S. epidermidis'', other CoNS<br />
<br />
==== ''Streptococcus'' species ====<br />
<br />
* GPC pairs & chains<br />
* Catalase -<br />
<br />
Lancefield grouping mainly used for ID<br />
{| class="wikitable"<br />
|+<br />
!Lancefield Grouping<br />
!Organism<br />
!Features<br />
!Clinical Relevance<br />
|-<br />
|Group A<br />
|''S. pyogenes''<br />
|<br />
* Beta-heme<br />
* PYR +<br />
|iGAS<br />
|-<br />
|Group B<br />
|''S. agalactiae''<br />
|<br />
* Beta-heme<br />
|<br />
|-<br />
| rowspan="2" |Group D<br />
|''S. bovis''<br />
|<br />
|<br />
|-<br />
|Enterococcus<br />
<br />
<br />
|<br />
|<br />
|-<br />
|Group C<br />
| rowspan="2" |''Streptococcus dysgalactiae'' subsp ''equisimilis''<br />
| rowspan="2" |Beta-heme<br />
| rowspan="2" |Normally commensal<br />
|-<br />
|Group G<br />
|-<br />
|<br />
|''S. pneumoniae''<br />
|<br />
* Alpha-heme<br />
* Bile soluble<br />
* Optochin sensitive (≥14mm)<br />
|<br />
|-<br />
|<br />
|Viridans Streptococci<br />
|<br />
|<br />
|}<br />
Catalase<br />
<br />
Oxidase<br />
<br />
PYR<br />
<br />
Mycology<br />
<br />
* Malassezia furfur = Tinea versicolour = budding yeast and hyphae in 10% KOH ("spaghetti and meatballs")<br />
* Candida albicans = polymorphic, chlamydospore +, germ tube +, urea -<br />
* Candida auris = germ tube -<br />
* Cryptococcus = germ tube -, india ink +, urea +<br />
<br />
Parasitology<br />
<br />
* Definitive/true host = where parasite develops into sexually mature (adult) form<br />
* Intermediate/secondary host = in-between host where parasite is sexually immature (e.g., larvae)<br />
* Entamoeba histolytica = spoke-like central karyosome(s)<br />
* Trichomonas vaginalis = one nuclei (often oval and to one side), flagella<br />
* Balantidium coli = large, ciliated<br />
* Schistosoma = egg with prominent spine/spike<br />
* Enterobius vermicularis = pinworm, egg is elongated oval with one side flattened<br />
* Strongyloides = larvae migrating through agar<br />
<br />
== Polymerase Chain Reaction ==<br />
<br />
* Taq polymerase used along with dNTPs (nucleotides for elongation), and primers (DNA or RNA sequence of interest)<br />
* Buffer pH at 8.0-9.5, include salts MgCl<sub>2</sub> and KCl<br />
* Amplified through multiple cycles (usually 25-30)<br />
* 95C denature - 60C anneal - 72C extend<br />
* qPCR provides amplification and detection together<br />
** detect products as they're produced<br />
** use fluorescent dye<br />
*** SYBR green or Taqman probe<br />
** SYBR green binds to any double-stranded DNA and fluoresces (more DNA produced = more fluorescence)<br />
** Taqman is more specific, and binds to a specific target section<br />
*** 5' fluorescent dye and 3' quencher<br />
*** No fluorescence when dye and quencher are close together<br />
*** During PCR, the extension of polymerase will cut the Taqman probe with an exonuclease, releasing the fluorescent probe<br />
*** As the probe is cut away from the quencher, a signal is released<br />
*** As amplification continues, more probes are separated from the quencher resulting in a larger signal<br />
** Get amplification curve over ~ 40 cycles<br />
*** Baseline phase (little fluorescent signal)<br />
*** Exponential phase as PCR product amplifies significantly ~ cycles 16-25<br />
*** Stationary phase once components are used up and no further amplification occurs<br />
** Threshold line is the point where there is a certain level of fluorescence above the background signal (set per instrument)<br />
** Cycle threshold (Ct) is the amount of cycles required to reach the threshold line<br />
*** If there's less target DNA/RNA present, it will take more cycles to amplify to this level = higher Ct<br />
*** If there's more target DNA/RNA present, it will take fewer cycles to reach this level = lower Ct<br />
*** Can use known standards to get absolute quantitation of target present by comparing the curves<br />
<br />
== MALDI-ToF ==<br />
Matrix-assisted laser desorption ionization time-of-flight<br />
<br />
* Laser vapourizes complex molecules into ionized protein molecules<br />
** Desorption removes molecules from sample<br />
** Ionization produces positively charged proteins that move through mass spec tube<br />
* Matrix (cinnamic acid) absorbs energy and protects sample<br />
* Measure mass-to-charge (m/z) ratio of molecules<br />
* Generates mass spectrum based on the flight time (speed) of the molecules = mass of ions<br />
** Smaller ions move faster<br />
* Compare results to database of known organisms</div>
Admin
https://medlabwiki.com/index.php?title=Hematology_Calculations&diff=202
Hematology Calculations
2025-02-21T07:38:48Z
<p>Admin: </p>
<hr />
<div>The following are common calculations used in the hematology discipline.<br />
<br />
==== RBC Indices ====<br />
There are 3 RBC indices that are calculated from measured RBC parameters: MCH, MCV, MCHC.<br />
<br />
==== Mean Cell Hemoglobin MCH (g/L) ====<br />
Average amount of hemoglobin present per red blood cell.<br />
<br />
<math display="block">MCH=\frac{HGB}{RBC}</math><br />
<br />
==== Mean Cell Volume MCV (fL) ====<br />
Average size (volume) of red blood cell.<br />
<br />
<math display="block">MCV=\frac{HCT*1000}{RBC}</math><br />
<br />
==== Mean Cell Hemoglobin Concentration MCHC (g/L) ====<br />
<math display="block">MCHC=\frac{HGB}{HCT}</math><br />
<br />
==== Rule of Three ====<br />
In normal RBCs, the HCT value should be approximately 3x the hemoglobin. Used as a quick check of the CBC results for interfering substances or other issues with the blood.<br />
<br />
<math display="block">\frac{HGB*3}{1000}=HCT\pm0.03</math><br />
<br />
==== Citrate Adjustment for High Hematocrit ====<br />
Used when hematocrit > 0.55 L/L as high hematocrit means that there is less plasma present (therefore, the plasma-anticoagulant ratio is incorrect). This can result in excess sodium citrate, which can falsely prolong the clotting time.<br />
<br />
<math display="block">C=(1.85*10^{-3})(100-HCT)(V)</math><br />
<br />
* C = citrate volume that needs to be remaining in tube<br />
* HCT = hematocrit<br />
*V = volume of blood drawn<br />
Then, use this value to determine that volume of citrate that needs to be removed.<br />
<br />
<math display="block">R=V_c-C</math><br />
<br />
* R = volume to be removed from tube<br />
* V<sub>c</sub> = volume of citrate present in tube<br />
* C = citrate volume remaining<br />
<br />
==== Reticulocyte Count (%) ====<br />
For 1000 RBCs<br />
<br />
<math display="block">\mbox{Relative reticulocyte count}=\frac{\mbox{Retics per 1000 RBCs}}{10}</math><br />
<br />
For >1000 RBCs<br />
<br />
<math display="block">\mbox{Relative reticulocyte count}=\frac{Retics*1000}{\mbox{RBC count}}</math><br />
<br />
==== Corrected Reticulocyte Count (%) ====<br />
The retic count should be corrected if there is a low hematocrit (less RBCs present), as this will falsely increase the reticulocyte count.<br />
<br />
<math display="block">\mbox{Corrected retic count}=\frac{\%\mbox{ Relative Retics * Patient HCT}}{\mbox{Average Normal HCT}}</math><br />
<br />
* Average normal HCT (male): 0.45 L/L<br />
* Average normal HCT (female): 0.42 L/L<br />
<br />
==== Absolute Reticulocyte Count (x10<sup>9</sup>/L) ====<br />
To determine the actual number of retics present in the blood.<br />
<br />
<math display="block">\mbox{Abs Retic}=\frac{\%\mbox{ Relative Retics * RBC}}{100}</math><br />
<br />
==== Corrected WBC Count for NRBC ====<br />
Used to correct the WBC count for NRBCs as they may be mistaken for WBCs by the analyzer, giving a falsely elevated result.<br />
<br />
<math display="block">\mbox{Corrected WBC}=\frac{\mbox{100 * WBC Count}}{100+NRBC}</math><br />
<br />
* NRBC = # NRBCs counted per 100 WBC<br />
<br />
==== International Normalized Ratio (INR) ====<br />
<math display="block">INR=\left ( \frac{\mbox{Patient PT}}{\mbox{Control PT}} \right )^{ISI}</math><br />
<br />
==== Neubauer Chamber Total Cell Counts ====<br />
To determine cell counts based on the amount of cells counted in the Neubauer Chamber. Values change depending on the fluid and cell being counted (fluid may be diluted, and the amount of squares counted depends on the cell type)<br />
[[File:Neubauer counts.jpg|thumb|Neubauer counts calculation for various fluids.]]<br />
<br />
* Average cell count = average (taken using both sides of the chamber)<br />
* DF = dilution factor (reciprocal of dilution)<br />
<br />
<br />
<br />
{| class="wikitable"<br />
|+<br />
|Fluid<br />
|Cell Type<br />
|Squares Counted<br />
|Dilution<br />
|DF<br />
|-<br />
| rowspan="3" |CSF<br />
| rowspan="3" |All cells! (WBC & RBC)<br />
| rowspan="3" |9 (all)<br />
|Clear: none<br />
|1<br />
|-<br />
|Bloody WBC: 1:2<br />
|2<br />
|-<br />
|Bloody: 1:10-1:200<br />
|10-200<br />
|-<br />
| rowspan="2" |Whole Blood<br />
|WBCs<br />
|4 (outer corners)<br />
|1:20<br />
|20<br />
|-<br />
|Platelets<br />
|1 (large central square)<br />
|1:100<br />
|100<br />
|-<br />
|Synovial Fluid<br />
|<br />
|<br />
|<br />
|<br />
|}<br />
__NOEDITSECTION__</div>
Admin
https://medlabwiki.com/index.php?title=Hematology_Calculations&diff=201
Hematology Calculations
2025-02-21T07:36:36Z
<p>Admin: Created page with "The following are common calculations used in the hematology discipline. ==== RBC Indices ==== There are 3 RBC indices that are calculated from measured RBC parameters: MCH, MCV, MCHC. ==== Mean Cell Hemoglobin MCH (g/L) ==== Average amount of hemoglobin present per red blood cell. <math display="block">MCH=\frac{HGB}{RBC}</math> ==== Mean Cell Volume MCV (fL) ==== Average size (volume) of red blood cell. <math display="block">MCV=\frac{HCT*1000}{RBC}</math> ==== M..."</p>
<hr />
<div>The following are common calculations used in the hematology discipline.<br />
<br />
==== RBC Indices ====<br />
There are 3 RBC indices that are calculated from measured RBC parameters: MCH, MCV, MCHC.<br />
<br />
==== Mean Cell Hemoglobin MCH (g/L) ====<br />
Average amount of hemoglobin present per red blood cell.<br />
<br />
<math display="block">MCH=\frac{HGB}{RBC}</math><br />
<br />
==== Mean Cell Volume MCV (fL) ====<br />
Average size (volume) of red blood cell.<br />
<br />
<math display="block">MCV=\frac{HCT*1000}{RBC}</math><br />
<br />
==== Mean Cell Hemoglobin Concentration MCHC (g/L) ====<br />
<math display="block">MCHC=\frac{HGB}{HCT}</math><br />
<br />
==== Rule of Three ====<br />
In normal RBCs, the HCT value should be approximately 3x the hemoglobin. Used as a quick check of the CBC results for interfering substances or other issues with the blood.<br />
<br />
<math display="block">\frac{HGB*3}{1000}=HCT\pm0.03</math><br />
<br />
==== Citrate Adjustment for High Hematocrit ====<br />
Used when hematocrit > 0.55 L/L as high hematocrit means that there is less plasma present (therefore, the plasma-anticoagulant ratio is incorrect). This can result in excess sodium citrate, which can falsely prolong the clotting time.<br />
<br />
<math display="block">C=(1.85*10^{-3})(100-HCT)(V)</math><br />
<br />
* C = citrate volume that needs to be remaining in tube<br />
* HCT = hematocrit<br />
* V = volume of blood drawnThen, use this value to determine that volume of citrate that needs to be removed.<br />
<math display="block">R=V_c-C</math><br />
<br />
* R = volume to be removed from tube<br />
* V<sub>c</sub> = volume of citrate present in tube<br />
* C = citrate volume remaining<br />
<br />
==== Reticulocyte Count (%) ====<br />
For 1000 RBCs<br />
<br />
<math display="block">\mbox{Relative reticulocyte count}=\frac{\mbox{Retics per 1000 RBCs}}{10}</math><br />
<br />
For >1000 RBCs<br />
<br />
<math display="block">\mbox{Relative reticulocyte count}=\frac{Retics*1000}{\mbox{RBC count}}</math><br />
<br />
==== Corrected Reticulocyte Count (%) ====<br />
The retic count should be corrected if there is a low hematocrit (less RBCs present), as this will falsely increase the reticulocyte count.<br />
<br />
<math display="block">\mbox{Corrected retic count}=\frac{\%\mbox{ Relative Retics * Patient HCT}}{\mbox{Average Normal HCT}}</math><br />
<br />
* Average normal HCT (male): 0.45 L/L<br />
* Average normal HCT (female): 0.42 L/L<br />
<br />
==== Absolute Reticulocyte Count (x10<sup>9</sup>/L) ====<br />
To determine the actual number of retics present in the blood.<br />
<br />
<math display="block">\mbox{Abs Retic}=\frac{\%\mbox{ Relative Retics * RBC}}{100}</math><br />
<br />
==== Corrected WBC Count for NRBC ====<br />
Used to correct the WBC count for NRBCs as they may be mistaken for WBCs by the analyzer, giving a falsely elevated result.<br />
<br />
<math display="block">\mbox{Corrected WBC}=\frac{\mbox{100 * WBC Count}}{100+NRBC}</math><br />
<br />
* NRBC = # NRBCs counted per 100 WBC<br />
<br />
==== International Normalized Ratio (INR) ====<br />
<math display="block">INR=\left ( \frac{\mbox{Patient PT}}{\mbox{Control PT}} \right )^{ISI}</math><br />
<br />
==== Neubauer Chamber Total Cell Counts ====<br />
To determine cell counts based on the amount of cells counted in the Neubauer Chamber. Values change depending on the fluid and cell being counted (fluid may be diluted, and the amount of squares counted depends on the cell type)<br />
[[File:Neubauer counts.jpg|thumb|Neubauer counts calculation for various fluids.]]<br />
<br />
* Average cell count = average (taken using both sides of the chamber)<br />
* DF = dilution factor (reciprocal of dilution)<br />
<br />
<br />
<br />
{| class="wikitable"<br />
|+<br />
|Fluid<br />
|Cell Type<br />
|Squares Counted<br />
|Dilution<br />
|DF<br />
|-<br />
| rowspan="3" |CSF<br />
| rowspan="3" |All cells! (WBC & RBC)<br />
| rowspan="3" |9 (all)<br />
|Clear: none<br />
|1<br />
|-<br />
|Bloody WBC: 1:2<br />
|2<br />
|-<br />
|Bloody: 1:10-1:200<br />
|10-200<br />
|-<br />
| rowspan="2" |Whole Blood<br />
|WBCs<br />
|4 (outer corners)<br />
|1:20<br />
|20<br />
|-<br />
|Platelets<br />
|1 (large central square)<br />
|1:100<br />
|100<br />
|-<br />
|Synovial Fluid<br />
|<br />
|<br />
|<br />
|<br />
|}<br />
__NOEDITSECTION__</div>
Admin
https://medlabwiki.com/index.php?title=File:Neubauer_counts.jpg&diff=200
File:Neubauer counts.jpg
2025-02-21T07:34:58Z
<p>Admin: </p>
<hr />
<div>Equations for calculating the cell counts in various types of fluids (with units)</div>
Admin
https://medlabwiki.com/index.php?title=Hematology&diff=199
Hematology
2025-02-21T07:16:12Z
<p>Admin: </p>
<hr />
<div>[[Blood Basics]]<br />
<br />
[[Specimen Processing (Hematology)]]<br />
<br />
[[Hematology Calculations]]<br />
<br />
[[Hematopoiesis]]<br />
<br />
[[Complete Blood Count (CBC)]]<br />
<br />
[[Coagulation]]<br />
<br />
[[Coagulation Testing]]<br />
<br />
[[Cellavision]]<br />
<br />
==== Red Blood Cell Morphology and Conditions ====<br />
[[Red Blood Cell Morphology]]<br />
<br />
[[Red Blood Cell Conditions]]<br />
<br />
==== Leukocyte Conditions ====<br />
[[Comparison of Leukocyte Conditions]]<br />
<br />
[[Inherited Qualitative Abnormalities]]<br />
<br />
==== Cancers & Bone Marrow Disorders ====<br />
[[Myelodysplastic Syndromes]]<br />
<br />
[[Myeloproliferative Disorders]]</div>
Admin
https://medlabwiki.com/index.php?title=Safety&diff=198
Safety
2025-02-20T23:10:24Z
<p>Admin: </p>
<hr />
<div>Biological Safety<br />
<br />
* Universal precautions: first guidelines, centered around blood-borne pathogen precautions<br />
* Body substance isolation (BSI): updated guidelines for protection against all bodily fluids that may potentially transmit disease, as well as additional protection against certain diseases (e.g., airborne disease)<br />
* Routine practises and additional precautions (standard precautions):<br />
** Assumption that all patients may possibly be infectious even without symptoms<br />
** Routine use of PPE and practises (e.g., handwashing) to prevent the spread of disease<br />
** If there are specific infection control concerns, then additional precautions may be used<br />
*** Contact<br />
*** Droplet<br />
*** Airborne<br />
S<br />
<br />
* Sterilization: kills all microbes, including spores and cysts<br />
* Disinfection: process that kills many organisms, but not necessary all organisms, especially resistant forms like spores<br />
** High level disinfection: complete elimination of all organisms on a device, except for small numbers of bacterial spores<br />
* 1% sodium hypochlorite for spot cleaning<br />
* 10% sodium hypochlorite for disinfecting spills<br />
* 2% glutaraldehyde is high level disinfectant<br />
<br />
Sterilization<br />
<br />
* Dry heat sterilization using only heat (oxidation kills organisms)<br />
* Useful for oils, powders, and solid materials<br />
* 160C for 60min or 170C for 30min<br />
* Spore test using ''Bacillus subtilus''<br />
<br />
* Moist Heat autoclave (coagulate and denature proteins)<br />
** 121C @ 15 psi for 15-30min<br />
** Useful for wide variety of materials, including liquids (won't evaporate)<br />
*** Avoid oils and powders (repel moisture)<br />
*** Blood and serum will lyse/coagulate<br />
*** Spore test using ''Geobacillus stearothermophilus''<br />
* UV Sterilization<br />
** 265nm to damage DNA<br />
** Does not penetrate<br />
* Ionizing radiation<br />
** Cobalt-60<br />
* Gas Sterilization<br />
** Ethylene oxide (alkylating agent - blocks metabolism)<br />
** Requires longer exposure (1-6 hours)<br />
** Useful for larger or sensitize items<br />
<br />
Sterilization Controls<br />
<br />
* Autoclave: ''Geobacillus stearothermophilus''<br />
* ETO and dry heat: ''Bacillus subtilis''<br />
* Spore strips: clear broth = inactivated, turbid broth = growth<br />
* Chemical indicators (e.g., autoclave tape) that changes colour if correct temperature is reached<br />
<br />
Air Filtration<br />
<br />
* HEPA filters 0.3μm<br />
* Class I BSC<br />
** Protect only the worker and environment (not items within BSC)<br />
** Draw in room air through front opening<br />
* Class II BSC (Risk group 1-3)<br />
** Protects worker, environment, and items within BSC<br />
** Draws air through front sash into grill and filter<br />
* Class III BSC (Risk group 1-4)<br />
** Protects worker, environment, and items within BSC<br />
** Inside of BSC is completed enclosed<br />
*** Use attached gloves to handle items<br />
** Air is filtered twice</div>
Admin
https://medlabwiki.com/index.php?title=Safety&diff=197
Safety
2025-02-20T22:45:29Z
<p>Admin: Created page with "Biological Safety * Universal precautions: first guidelines, centered around blood-borne pathogen precautions * Body substance isolation (BSI): updated guidelines for protection against all bodily fluids that may potentially transmit disease, as well as additional protection against certain diseases (e.g., airborne disease) * Routine practises and additional precautions (standard precautions): ** Assumption that all patients may possibly be infectious even without sympt..."</p>
<hr />
<div>Biological Safety<br />
<br />
* Universal precautions: first guidelines, centered around blood-borne pathogen precautions<br />
* Body substance isolation (BSI): updated guidelines for protection against all bodily fluids that may potentially transmit disease, as well as additional protection against certain diseases (e.g., airborne disease)<br />
* Routine practises and additional precautions (standard precautions):<br />
** Assumption that all patients may possibly be infectious even without symptoms<br />
** Routine use of PPE and practises (e.g., handwashing) to prevent the spread of disease<br />
** If there are specific infection control concerns, then additional precautions may be used<br />
*** Contact<br />
*** Droplet<br />
*** Airborne</div>
Admin
https://medlabwiki.com/index.php?title=Main_Page&diff=196
Main Page
2025-02-20T22:35:07Z
<p>Admin: </p>
<hr />
<div><strong>Welcome to MedLabWiki, your non-reviewed source for all things in medical laboratory science! Please browse by the following disciplines:</strong><br />
{| class="wikitable"<br />
|+<br />
![[Biochemistry]]<br />
![[Hematology]]<br />
![[Histology]]<br />
![[Microbiology]]<br />
![[Transfusion Science]]<br />
![[Phlebotomy]]<br />
![[Quality]]<br />
|-<br />
|Clinical chemistry & instrumentation<br />
|Blood & blood components<br />
|Specimen preparation & staining<br />
|Microbes & infection disease testing<br />
|Blood banking<br />
|Specimen procurement<br />
|Quality management<br />
|-<br />
| colspan="3" |[[Safety]]<br />
| colspan="4" |Quality<br />
|}<br />
[[Other Topics]] (for future discussion)<br />
<br />
Consult the [[mediawikiwiki:Special:MyLanguage/Help:Contents|User's Guide]] for information on using the wiki software.<br />
<br />
== Getting started ==<br />
* [https://www.mediawiki.org/wiki/Special:MyLanguage/Manual:Configuration_settings Configuration settings list]<br />
* [https://www.mediawiki.org/wiki/Special:MyLanguage/Manual:FAQ MediaWiki FAQ]<br />
* [https://lists.wikimedia.org/postorius/lists/mediawiki-announce.lists.wikimedia.org/ MediaWiki release mailing list]<br />
* [https://www.mediawiki.org/wiki/Special:MyLanguage/Localisation#Translation_resources Localise MediaWiki for your language]<br />
* [https://www.mediawiki.org/wiki/Special:MyLanguage/Manual:Combating_spam Learn how to combat spam on your wiki]</div>
Admin
https://medlabwiki.com/index.php?title=Microbiology_Quick_Reference&diff=195
Microbiology Quick Reference
2025-02-20T20:33:44Z
<p>Admin: </p>
<hr />
<div>== Microbiology Agars ==<br />
{| class="wikitable"<br />
|+<br />
!Agar<br />
!Enrichment<br />
!Selective<br />
!Differential Features<br />
!Use<br />
|-<br />
|Blood<br />
|5-10% sheep blood<br />
|<br />
|Shows hemolysis<br />
|General growth medium<br />
|-<br />
|Chocolate<br />
|5-10% lysed sheep blood<br />
2% hemoglobin + supplements<br />
|<br />
|<br />
|Growth of fastidious organisms<br />
|-<br />
|CNA<br />
|5-10% sheep blood<br />
|Gram positives grow<br />
<br />
* Colistin<br />
* Naladixic acid<br />
|Shows hemolysis<br />
|Growth of gram positives and yeast<br />
|-<br />
|MacConkey<br />
|<br />
|Gram negatives grow<br />
<br />
* Bile salts<br />
* Crystal violet<br />
|Shows lactose fermentation<br />
|Grow of gram negatives<br />
|}<br />
{| class="wikitable"<br />
!Agar<br />
!Features<br />
!Use<br />
|-<br />
|Meuller Hinton<br />
|<br />
|<br />
|-<br />
|MH + Sheep's blood<br />
|<br />
* Enrichment: sheep blood<br />
|AST for specific organisms<br />
<br />
* ''Streptococcus pneumoniae''<br />
|-<br />
|Thioglycollate broth<br />
|<br />
* Enrichment: hemin & vitamin K<br />
* Differential: O<sub>2</sub> use based on location of growth in tube<br />
|General growth medium, allows presumption of atmospheric growth conditions<br />
|-<br />
|Enrichment Media<br />
|<br />
* Usually broth<br />
* Grows fastidious or a specific organism from mixed specimens<br />
* Contain differential reagents to suppress normal flora for a short period of time<br />
** Requires subculture within ~ 12-18h<br />
|<br />
* Selenite broth<br />
* Tetrathionate broth<br />
* Brain-heart Infusion broth<br />
* Cooked meat broth<br />
|-<br />
|Sorbitol MacConkey<br />
|<br />
* Selective: for gram negatives<br />
* Differential: sorbitol fermentation<br />
|Enterohemorrhagic ''E. coli'' (non-sorbitol fermenters) vs other ''E. coli'' (sorbitol fermenters)<br />
|-<br />
|Salmonella-Shigella<br />
|<br />
* Selective: bile salts, sodium citrate, brilliant green<br />
** Selects for gram negative enteric pathogens<br />
* Differential: lactose fermentation + H<sub>2</sub>S production<br />
|Isolate enteric pathogens<br />
|-<br />
|Hektoen Agar<br />
|<br />
* Selective: bile salts<br />
** Selects for gram negative, mostly enteric pathogens<br />
* Differential: lactose, sucrose, and salicin fermentation + H<sub>2</sub>S production<br />
|Isolate enteric pathogens<br />
|-<br />
|Cefsulodin Irgasan Novobiocin (CIN)<br />
|<br />
* Selective: cefsulodin, irgasan, novobiocin, sodium desoxycholate, crystal violet<br />
** Inhibit gram + and normal stool flora<br />
* Differential: mannitol fermentation<br />
|Isolate ''Yersinia enterocolitica''<br />
|-<br />
|Campylobacter agar<br />
|<br />
* Enrichment: 10% sheep blood<br />
* Selective: <br />
** vancomycin (inhibit gram +)<br />
** amphotericin B + polymyxin B (inhibit yeast/fungus)<br />
** trimethoprim (prevent ''Proteus'' swarming)<br />
** cefoperazone (inhibit gram -)<br />
** Sodium bisulfite (creates microaerophillic environment)<br />
|Isolate ''Campylobacter''<br />
|-<br />
|<br />
|<br />
|<br />
|-<br />
|Mannitol salt agar<br />
|<br />
* Selective: 7.5% salt<br />
** Selects for halophiles<br />
* Differential: mannitol fermentation<br />
|Screen for ''Staphylococcus aureus''<br />
|-<br />
|New York City agar<br />
|<br />
* Enrichment: lysed blood, yeast dialysate, and plasma<br />
* Selective: vancomycin, colistin, amphotericin B, and trimethoprim <br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|}<br />
<br />
== Stains ==<br />
* Gram stain<br />
* Ziehl-Neelsen (acid fast)<br />
** Uses heat for uptake of carbolfuchsin<br />
* Kinyoun (acid fast)<br />
** Higher phenol concentration for uptake of carbolfuchsin<br />
* Auramine/Auramine-Rhodamine (acid fast)<br />
** fluorescent dye binds to mycolic acids<br />
* Acridine Orange (organisms without cell wall)<br />
** fluorescent dye binds to nucleic acid in cells<br />
** useful for organisms without cell wall (e.g., ''Mycoplasma'')<br />
* Calcofluor white (fungi)<br />
** Fluorescent dye binds to cellulose and chitin<br />
<br />
'''K'''inyoun = '''cold''', '''Acrid'''ine = nucleic '''acids''', '''C'''alcofluor = '''c'''hitin<br />
<br />
== Biochemical Tests ==<br />
{| class="wikitable"<br />
|+<br />
!Test<br />
!Purpose<br />
!Mechanism<br />
!Results<br />
|-<br />
|Hugh-Leifson Oxidation/Fermentation Test<br />
|Determines if organism can metabolize carbohydrates<br />
|Incubate tubes with 1% glucose + peptones<br />
Check for pH change in aerobic and anaerobic tubes<br />
<br />
* Fermenter: both +<br />
* Oxidizer: aerobic + only<br />
* Non-fermenter/oxidizer: both -<br />
|Positive: yellow<br />
Negative: green<br />
|-<br />
|ONPG<br />
|Differentiate late lactose fermenters from non-lactose fermenters<br />
<br />
* LLF: have β-galactosidase but not permease to allow cell uptake (may mutate or turn gene on after exposure to lactose)<br />
* NLF: no β-galactosidase (can't utilized lactose)<br />
|Use ONPG disk, which is similar to lactose but small enough to diffuse without permease<br />
|Positive LLF: any yellow<br />
Negative NLF: colourless<br />
|-<br />
|TSI (Triple Sugar Iron)<br />
|Detect fermentation of glucose, lactose, and/or sucrose<br />
Detect production of gases and H<sub>2</sub>S<br />
|0.1% glucose is used up first, then either:<br />
<br />
* Non-fermenters use peptones (alkaline in slant)<br />
* Fermenters use lactose and/or sucrose (acid in both butt and slant)<br />
|Glucose only: NA/A (pink slant, yellow butt)<br />
Multiple carbohydrates: A/A (yellow slant and butt)<br />
Aerobic organism (no fermentation): NA/NC (red slant and butt)<br />
May also produce gas and/or H<sub>2</sub>S<br />
|-<br />
|MRVP<br />
|Used to determine type of pyruvate fermentation pathway used<br />
<br />
* MR uses mixed-acid pathway<br />
* VP uses 2,3-butanediol pathway<br />
|Mixed acid fermentation produces acid end-products (lactic acid and acetic acid), causing pH change<br />
2,3-butanediol pathway produces acetoin<br />
|<br />
|-<br />
|Decarboxylation<br />
|<br />
|<br />
|<br />
|-<br />
|Arginine Dihydrolase<br />
|<br />
|<br />
|<br />
|-<br />
|Phenylalanine Deaminase (PPD)<br />
|Used to test for phenylalanine deaminase<br />
<br />
* Present in gram negative bacilli<br />
|<br />
|Positive: green<br />
Negative: yellow<br />
|-<br />
|Simmon's Citrate<br />
|<br />
|<br />
|Positive: blue or green with growth<br />
Negative: green, no growth<br />
|-<br />
|Gelatin test<br />
|<br />
|<br />
|<br />
|-<br />
|Indole<br />
|<br />
|<br />
|<br />
|-<br />
|Sulfide-Indole-Motility (SIM)<br />
|<br />
|<br />
|<br />
|-<br />
|Nitrate Test<br />
|Determines whether organism has nitrate reductase to produce O<sub>2</sub> anaerobically<br />
|Nitrate reductase converts nitrate -> nitrite (NO<sub>2</sub>)<br />
Some organisms further break down nitrite to nitrogen gas<br />
|If red at first tube = nitrites positive<br />
If not red, then but add zinc<br />
<br />
* Red = negative (original nitrates present)<br />
* No colour = positive (nitrite reduced to N2)<br />
|-<br />
|Urea Test<br />
|<br />
|<br />
|<br />
|}<br />
{| class="wikitable"<br />
|+<br />
!Test<br />
!Positive QC<br />
!Negative QC<br />
!Uses<br />
|-<br />
|Catalase<br />
|''Staphylococcus spp.''<br />
|<br />
|<br />
|-<br />
|Coagulase<br />
| rowspan="2" |''S. aureus''<br />
| rowspan="2" |Other ''Staphylococcus''<br />
|<br />
|-<br />
|Staphaureux (Latex agglutination)<br />
|<br />
|-<br />
|PYR<br />
|''S. lugdunensis''<br />
|<br />
|<br />
|}<br />
<br />
==== ''Staphylococcus'' species ====<br />
''Staphylococcus aureus''<br />
<br />
* GPC clusters<br />
* Catalase +<br />
* Coagulase +<br />
* Staphaureux +<br />
<br />
If coagulase/Staphaureux negative, then CoNS:<br />
<br />
* ''S. lugdunensis'': PYR +<br />
* ''S. saprophyticus'' (females 12-60): Novobiocin resistant<br />
* Others: ''S. epidermidis'', other CoNS<br />
<br />
==== ''Streptococcus'' species ====<br />
<br />
* GPC pairs & chains<br />
* Catalase -<br />
<br />
Lancefield grouping mainly used for ID<br />
{| class="wikitable"<br />
|+<br />
!Lancefield Grouping<br />
!Organism<br />
!Features<br />
!Clinical Relevance<br />
|-<br />
|Group A<br />
|''S. pyogenes''<br />
|<br />
* Beta-heme<br />
* PYR +<br />
|iGAS<br />
|-<br />
|Group B<br />
|''S. agalactiae''<br />
|<br />
* Beta-heme<br />
|<br />
|-<br />
| rowspan="2" |Group D<br />
|''S. bovis''<br />
|<br />
|<br />
|-<br />
|Enterococcus<br />
<br />
<br />
|<br />
|<br />
|-<br />
|Group C<br />
| rowspan="2" |''Streptococcus dysgalactiae'' subsp ''equisimilis''<br />
| rowspan="2" |Beta-heme<br />
| rowspan="2" |Normally commensal<br />
|-<br />
|Group G<br />
|-<br />
|<br />
|''S. pneumoniae''<br />
|<br />
* Alpha-heme<br />
* Bile soluble<br />
* Optochin sensitive (≥14mm)<br />
|<br />
|-<br />
|<br />
|Viridans Streptococci<br />
|<br />
|<br />
|}<br />
Catalase<br />
<br />
Oxidase<br />
<br />
PYR<br />
<br />
== Polymerase Chain Reaction ==<br />
<br />
* Taq polymerase used along with dNTPs (nucleotides for elongation), and primers (DNA or RNA sequence of interest)<br />
* Buffer pH at 8.0-9.5, include salts MgCl<sub>2</sub> and KCl<br />
* Amplified through multiple cycles (usually 25-30)<br />
* 95C denature - 60C anneal - 72C extend<br />
* qPCR provides amplification and detection together<br />
** detect products as they're produced<br />
** use fluorescent dye<br />
*** SYBR green or Taqman probe<br />
** SYBR green binds to any double-stranded DNA and fluoresces (more DNA produced = more fluorescence)<br />
** Taqman is more specific, and binds to a specific target section<br />
*** 5' fluorescent dye and 3' quencher<br />
*** No fluorescence when dye and quencher are close together<br />
*** During PCR, the extension of polymerase will cut the Taqman probe with an exonuclease, releasing the fluorescent probe<br />
*** As the probe is cut away from the quencher, a signal is released<br />
*** As amplification continues, more probes are separated from the quencher resulting in a larger signal<br />
** Get amplification curve over ~ 40 cycles<br />
*** Baseline phase (little fluorescent signal)<br />
*** Exponential phase as PCR product amplifies significantly ~ cycles 16-25<br />
*** Stationary phase once components are used up and no further amplification occurs<br />
** Threshold line is the point where there is a certain level of fluorescence above the background signal (set per instrument)<br />
** Cycle threshold (Ct) is the amount of cycles required to reach the threshold line<br />
*** If there's less target DNA/RNA present, it will take more cycles to amplify to this level = higher Ct<br />
*** If there's more target DNA/RNA present, it will take fewer cycles to reach this level = lower Ct<br />
*** Can use known standards to get absolute quantitation of target present by comparing the curves<br />
<br />
== MALDI-ToF ==<br />
Matrix-assisted laser desorption ionization time-of-flight<br />
<br />
* Laser vapourizes complex molecules into ionized protein molecules<br />
** Desorption removes molecules from sample<br />
** Ionization produces positively charged proteins that move through mass spec tube<br />
* Matrix (cinnamic acid) absorbs energy and protects sample<br />
* Measure mass-to-charge (m/z) ratio of molecules<br />
* Generates mass spectrum based on the flight time (speed) of the molecules = mass of ions<br />
** Smaller ions move faster<br />
* Compare results to database of known organisms</div>
Admin
https://medlabwiki.com/index.php?title=Microbiology_Quick_Reference&diff=194
Microbiology Quick Reference
2025-02-20T19:16:44Z
<p>Admin: </p>
<hr />
<div>Agars<br />
{| class="wikitable"<br />
|+<br />
!Agar<br />
!Enrichment<br />
!Selective<br />
!Differential Features<br />
!Use<br />
|-<br />
|Blood<br />
|5-10% sheep blood<br />
|<br />
|Shows hemolysis<br />
|General growth medium<br />
|-<br />
|Chocolate<br />
|5-10% lysed sheep blood<br />
2% hemoglobin + supplements<br />
|<br />
|<br />
|Growth of fastidious organisms<br />
|-<br />
|CNA<br />
|5-10% sheep blood<br />
|Gram positives grow<br />
<br />
* Colistin<br />
* Naladixic acid<br />
|Shows hemolysis<br />
|Growth of gram positives and yeast<br />
|-<br />
|MacConkey<br />
|<br />
|Gram negatives grow<br />
<br />
* Bile salts<br />
* Crystal violet<br />
|Shows lactose fermentation<br />
|Grow of gram negatives<br />
|}<br />
{| class="wikitable"<br />
!Agar<br />
!Features<br />
!Use<br />
|-<br />
|Meuller Hinton<br />
|<br />
|<br />
|-<br />
|MH + Sheep's blood<br />
|<br />
* Enrichment: sheep blood<br />
|AST for specific organisms<br />
<br />
* ''Streptococcus pneumoniae''<br />
|-<br />
|Thioglycollate broth<br />
|<br />
* Enrichment: hemin & vitamin K<br />
* Differential: O<sub>2</sub> use based on location of growth in tube<br />
|General growth medium, allows presumption of atmospheric growth conditions<br />
|-<br />
|Enrichment Media<br />
|<br />
* Usually broth<br />
* Grows fastidious or a specific organism from mixed specimens<br />
* Contain differential reagents to suppress normal flora for a short period of time<br />
** Requires subculture within ~ 12-18h<br />
|<br />
* Selenite broth<br />
* Tetrathionate broth<br />
* Brain-heart Infusion broth<br />
* Cooked meat broth<br />
|-<br />
|Sorbitol MacConkey<br />
|<br />
* Selective: for gram negatives<br />
* Differential: sorbitol fermentation<br />
|Enterohemorrhagic ''E. coli'' (non-sorbitol fermenters) vs other ''E. coli'' (sorbitol fermenters)<br />
|-<br />
|Salmonella-Shigella<br />
|<br />
* Selective: bile salts, sodium citrate, brilliant green<br />
** Selects for gram negative enteric pathogens<br />
* Differential: lactose fermentation + H<sub>2</sub>S production<br />
|Isolate enteric pathogens<br />
|-<br />
|Hektoen Agar<br />
|<br />
* Selective: bile salts<br />
** Selects for gram negative, mostly enteric pathogens<br />
* Differential: lactose, sucrose, and salicin fermentation + H<sub>2</sub>S production<br />
|Isolate enteric pathogens<br />
|-<br />
|Cefsulodin Irgasan Novobiocin (CIN)<br />
|<br />
* Selective: cefsulodin, irgasan, novobiocin, sodium desoxycholate, crystal violet<br />
** Inhibit gram + and normal stool flora<br />
* Differential: mannitol fermentation<br />
|Isolate ''Yersinia enterocolitica''<br />
|-<br />
|Campylobacter agar<br />
|<br />
* Enrichment: 10% sheep blood<br />
* Selective: <br />
** vancomycin (inhibit gram +)<br />
** amphotericin B + polymyxin B (inhibit yeast/fungus)<br />
** trimethoprim (prevent ''Proteus'' swarming)<br />
** cefoperazone (inhibit gram -)<br />
** Sodium bisulfite (creates microaerophillic environment)<br />
|Isolate ''Campylobacter''<br />
|-<br />
|<br />
|<br />
|<br />
|-<br />
|Mannitol salt agar<br />
|<br />
* Selective: 7.5% salt<br />
** Selects for halophiles<br />
* Differential: mannitol fermentation<br />
|Screen for ''Staphylococcus aureus''<br />
|-<br />
|New York City agar<br />
|<br />
* Enrichment: lysed blood, yeast dialysate, and plasma<br />
* Selective: vancomycin, colistin, amphotericin B, and trimethoprim <br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|}<br />
Stains<br />
<br />
* Gram stain<br />
* Ziehl-Neelsen (acid fast)<br />
** Uses heat for uptake of carbolfuchsin<br />
* Kinyoun (acid fast)<br />
** Higher phenol concentration for uptake of carbolfuchsin<br />
* Auramine/Auramine-Rhodamine (acid fast)<br />
** fluorescent dye binds to mycolic acids<br />
* Acridine Orange (organisms without cell wall)<br />
** fluorescent dye binds to nucleic acid in cells<br />
** useful for organisms without cell wall (e.g., ''Mycoplasma'')<br />
* Calcofluor white (fungi)<br />
** Fluorescent dye binds to cellulose and chitin<br />
<br />
'''K'''inyoun = '''cold''', '''Acrid'''ine = nucleic '''acids''', '''C'''alcofluor = '''c'''hitin<br />
{| class="wikitable"<br />
|+<br />
!Test<br />
!Positive QC<br />
!Negative QC<br />
!Uses<br />
|-<br />
|Catalase<br />
|''Staphylococcus spp.''<br />
|<br />
|<br />
|-<br />
|Coagulase<br />
| rowspan="2" |''S. aureus''<br />
| rowspan="2" |Other ''Staphylococcus''<br />
|<br />
|-<br />
|Staphaureux (Latex agglutination)<br />
|<br />
|-<br />
|PYR<br />
|''S. lugdunensis''<br />
|<br />
|<br />
|}<br />
<br />
==== ''Staphylococcus'' species ====<br />
''Staphylococcus aureus''<br />
<br />
* GPC clusters<br />
* Catalase +<br />
* Coagulase +<br />
* Staphaureux +<br />
<br />
If coagulase/Staphaureux negative, then CoNS:<br />
<br />
* ''S. lugdunensis'': PYR +<br />
* ''S. saprophyticus'' (females 12-60): Novobiocin resistant<br />
* Others: ''S. epidermidis'', other CoNS<br />
<br />
==== ''Streptococcus'' species ====<br />
<br />
* GPC pairs & chains<br />
* Catalase -<br />
<br />
Lancefield grouping mainly used for ID<br />
{| class="wikitable"<br />
|+<br />
!Lancefield Grouping<br />
!Organism<br />
!Features<br />
!Clinical Relevance<br />
|-<br />
|Group A<br />
|''S. pyogenes''<br />
|<br />
* Beta-heme<br />
* PYR +<br />
|iGAS<br />
|-<br />
|Group B<br />
|''S. agalactiae''<br />
|<br />
* Beta-heme<br />
|<br />
|-<br />
| rowspan="2" |Group D<br />
|''S. bovis''<br />
|<br />
|<br />
|-<br />
|Enterococcus<br />
<br />
<br />
|<br />
|<br />
|-<br />
|Group C<br />
| rowspan="2" |''Streptococcus dysgalactiae'' subsp ''equisimilis''<br />
| rowspan="2" |Beta-heme<br />
| rowspan="2" |Normally commensal<br />
|-<br />
|Group G<br />
|-<br />
|<br />
|''S. pneumoniae''<br />
|<br />
* Alpha-heme<br />
* Bile soluble<br />
* Optochin sensitive (≥14mm)<br />
|<br />
|-<br />
|<br />
|Viridans Streptococci<br />
|<br />
|<br />
|}<br />
Catalase<br />
<br />
Oxidase<br />
<br />
PYR</div>
Admin
https://medlabwiki.com/index.php?title=Red_Blood_Cell_Conditions&diff=193
Red Blood Cell Conditions
2025-02-18T23:41:43Z
<p>Admin: </p>
<hr />
<div>There are a variety of conditions that contribute to abnormal RBC function or counts.<br />
{| class="wikitable"<br />
|+<br />
!Condition<br />
!Physiology<br />
!WBC<br />
!RBC<br />
!HGB<br />
!HCT<br />
!MCV<br />
!MCH<br />
!MCHC<br />
!RDW<br />
!PLT<br />
!Morphology<br />
!Followup Tests<br />
|-<br />
|Blood loss/hemorrhage <br />
|<br />
|<br />
|N/↓<br />
|N<br />
|N<br />
|N<br />
|N<br />
|N<br />
|N<br />
|<br />
|Normal<br />
|<br />
|-<br />
|Iron Deficiency Anemia<br />
|Insufficient erythropoiesis<br />
|<br />
|N/↓<br />
|N/↓<br />
|↓<br />
|↓<br />
|↓<br />
|↓<br />
|↑<br />
|<br />
|Hypo/micro<br />
<br />
* Ovals, pencils<br />
* Tears, targets (occasional)<br />
|<br />
|-<br />
|Anemia of Chronic Inflammation<br />
|Insufficient erythropoiesis<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|Normal or Hypo/micro<br />
|<br />
|-<br />
|Sideroblastic Anemia<br />
|Ineffective erythropoiesis<br />
<br />
* Deficient protoporphyrin synthesis<br />
|<br />
|↓<br />
|↓<br />
|↓<br />
|N/↓<br />
|N/↓<br />
|N/↓<br />
|↑<br />
|<br />
|Dual population<br />
<br />
# Normochromic/normocytic<br />
# Hypo/micro<br />
<br />
Pappenheimers<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|Lead poisoning<br />
|<br />
|<br />
|↓<br />
|↓<br />
|↓<br />
|N/↓<br />
|N/↓<br />
|N/'''↓'''<br />
|N<br />
|<br />
|Normal OR hypo/micro<br />
<br />
* Stomatocytes<br />
* Coarse basophilic stippling<br />
|<br />
|-<br />
|Thalassemia<br />
|Ineffective erythropoiesis<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|Hypo/micro<br />
|<br />
|-<br />
|Megaloblastic Anemia<br />
|Ineffective erythropoiesis<br />
<br />
* Vitamin B12 deficiency<br />
* Folic acid deficiency<br />
* Certain cancers or drugs<br />
|<br />
|<br />
|<br />
|<br />
|↑<br />
|<br />
|N<br />
|<br />
|<br />
|Macrocytic/normochromic<br />
|<br />
|-<br />
|Liver disease<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|↑<br />
|<br />
|N<br />
|<br />
|<br />
|Macrocytic/normochromic<br />
|<br />
|-<br />
|Aplastic Anemia<br />
|Insufficient erythropoiesis<br />
<br />
* Hypocellularity due to autoimmune destruction<br />
|<br />
|<br />
|<br />
|<br />
|↑<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|}<br />
Insufficient Erythropoiesis<br />
<br />
* Iron deficiency anemia<br />
* Erythropoietin deficiency (renal disease)<br />
* Loss of erythroid precursors<br />
** Aplastic anemia (autoimmune)<br />
** Infection<br />
** Destruction/suppression of erythroid precursors (cancers, granulomas, fibrosis)<br />
Anemias<br />
<br />
* Ineffective erythropoiesis<br />
** Defective precursors made that are destroyed or function poorly<br />
* Insufficient erythropoiesis<br />
* Blood loss (acute or chronic)<br />
* Increased RBC destruction (hemolytic anemia)<br />
** Shortened cell survival<br />
** Intrinsic RBC defects<br />
** Extrinsic RBC defects</div>
Admin
https://medlabwiki.com/index.php?title=Complete_Blood_Count_(CBC)&diff=192
Complete Blood Count (CBC)
2025-02-18T21:32:53Z
<p>Admin: /* Calculated Parameters */</p>
<hr />
<div>{| class="wikitable"<br />
|+<br />
! colspan="2" |Parameter<br />
!Summary<br />
!RI Male<br />
!RI Female<br />
|-<br />
| colspan="2" |RBC count<br />
|<br />
|4.2-6.0×10<sup>12</sup>/L<br />
|3.8-5.2×10<sup>12</sup>/L<br />
|-<br />
| colspan="2" |HGB<br />
|<br />
|135-180 g/L<br />
|120-150 g/L<br />
|-<br />
| colspan="2" |HCT<br />
|<br />
|0.40-0.54 L/L<br />
|0.35-0.49 L/L<br />
|-<br />
| colspan="2" |MCH<br />
|HGB/RBC<br />
| colspan="2" |26-34 pg<br />
|-<br />
| colspan="2" |MCV<br />
|HCT*1000/RBC<br />
| colspan="2" |80-100 fL<br />
|-<br />
| colspan="2" |MCHC<br />
|HGB/HCT<br />
<br />
* >360 g/L hereditary spherocytosis (~50% of patients)<br />
<br />
* >380 g/L specimen integrity issue (Icterus, Lipemia, high WBC or cold agglutinins)<br />
| colspan="2" |320-360 g/L<br />
|-<br />
| colspan="2" |RDW<br />
|<br />
| colspan="2" |11.5-14.5%<br />
|-<br />
| colspan="2" |PLT count<br />
|<br />
| colspan="2" |150-450×10<sup>9</sup> /L<br />
|-<br />
|MPV<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
| colspan="2" |WBC count<br />
|<br />
| colspan="2" |3.6-10.6×10<sup>9</sup> /L<br />
|-<br />
| rowspan="5" |Relative WBC differential<br />
|Neutrophils<br />
|<br />
|<br />
|<br />
|-<br />
|Lymphocytes<br />
|<br />
|<br />
|<br />
|-<br />
|Monocytes<br />
|<br />
|<br />
|<br />
|-<br />
|Eosinophils<br />
|<br />
|<br />
|<br />
|-<br />
|Basophils<br />
|<br />
|<br />
|<br />
|-<br />
| rowspan="5" |Absolute WBC differential<br />
|Neutrophils<br />
|<br />
|<br />
|<br />
|-<br />
|Lymphocytes<br />
|<br />
|<br />
|<br />
|-<br />
|Monocytes<br />
|<br />
|<br />
|<br />
|-<br />
|Eosinophils<br />
|<br />
|<br />
|<br />
|-<br />
|Basophils<br />
|<br />
|<br />
|<br />
|}<br />
<br />
=== Calculated Parameters ===<br />
<math>MCH=\frac{HGB}{RBC}</math><br />
<br />
<math>MCV=\frac{HCT\ast 1000}{RBC}</math><br />
<br />
<math>MCHC=\frac{HGB}{HCT}</math><br />
<br />
=== Hemoglobin ===<br />
<br />
* Binds O2 in the lungs (↑ pH)<br />
** High O2 affinity required to keep O2 bound<br />
* Released O2 in tissues (↓ pH, ↑ pCO2)<br />
** Low O2 affinity required to release O2<br />
<br />
==== O2 Saturation Curve ====<br />
<br />
* 50% O2 saturation occurs at ~ 27 mmHg<br />
* Right shift = decreased affinity of hemoglobin = more O2 released to tissues<br />
** ↑ temperature<br />
** ↑ 2,3-BPG<br />
** ↓ pH (acidosis)<br />
** Abnormal hemoglobin variants with low O2 affinity<br />
** "Acid, drugs (2,3-BPG), and heat - all up oxygen to tissue"<br />
* Left shift = increased affinity of hemoglobin = less O2 released to tissues<br />
** ↓ temperature<br />
** ↓ 2,3-BPG<br />
** ↑ pH (alkalosis)<br />
** Abnormal hemoglobin variants with high O2 affinity<br />
<br />
Abnormal Hemoglobins<br />
<br />
* Variant hemoglobin structures<br />
* Dyshemoglobins<br />
** Methemoglobin - oxidized ferric [Fe<sup>3+</sup>] iron<br />
*** O2 can't bind properly, ↑ O2 affinity (left shift prevents O2 release)<br />
*** Acquired (drugs, meds) or congenital (abnormal globin chains or ability to reduce iron)<br />
*** Bluish-brown blood colour<br />
** Sulfhemoglobin<br />
*** Sulfur attached to hemoglobin<br />
*** Permanent inability to bind O2<br />
*** Acquired (drug-induced)<br />
*** Greenish blood colour<br />
** Carboxyhemoglobin<br />
*** Out-competes O2 (binds ~200x more tightly)<br />
*** Releases 10 000x slower<br />
<br />
Iron<br />
<br />
* Functional iron<br />
** ~70% hemoglobin (ferrous [Fe<sup>2+</sup>] state)<br />
** ~10% myoglobin (ferrous [Fe<sup>2+</sup>] state)<br />
** ~3% within enzymes<br />
* Stored Iron<br />
** ~20% in storage forms, mostly within liver<br />
** Ferritin (ferric [Fe<sup>3+</sup>] state) in liver<br />
*** Iron-Apoferritin complex keeps iron bound<br />
** Hemosiderin<br />
*** Intracellular storage form in liver, spleen, and bone marrow<br />
*** Formed from breakdown of ferritin aggregates<br />
* Transported iron<br />
** ~1% in plasma<br />
** Transferrin<br />
*** Transport protein in plasma to move iron between compartments<br />
*** Transport of iron absorbed from duodenum (small intestine) to bone marrow<br />
*** Produced by hepatocytes when ↓ iron<br />
**** Regulated by hepcidin (binds ferroportin to block uptake)</div>
Admin