View source for Chemistry Specimen Processing

Separate serum/plasma from blood cells within 2 hours

* For serum, need to wait for specimen to clot first (20-30 min)
Store samples at 4C when not being run

For longer-term storage, store at minimum -20C
{| class="wikitable"
|+
!Analyte
!Specimen Type
!Collection Media
!Collection Notes
!Reference Interval
|-
|Sodium
|
|Lithium heparin
|
|135 - 145 mmol/L
|-
|Potassium
|
|Lithium heparin
|
|3.5-5.0 mmol/L
|-
| rowspan="2" |Glucose
|Fasting
|
|
|4.1 - 5.6 mmol/L
|-
|Random
|
|
|
|-
| rowspan="2" |Creatinine
|Urine, 24 hour
|
|
|
|-
|Blood serum
|Lithium heparin
|
|
|-
|Serum Iron
|
|
|
|
|-
|Ferritin
|
|
|
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|-
|Total Iron Binding Capacity
|
|
|
|
|-
|% Transferrin Saturation
|
|
|
|20-55%
|-
| rowspan="3" |Urea
|Blood serum or plasma
|Lithium heparin
|
|2.1 - 7.1 mmol/L
|-
|Urine, random
|
|Use thymol preservative and refrigerate
|
|-
|Urine, 24 hour
|
|Use thymol preservative and refrigerate
|430 - 710 mmol/day
|-
| rowspan="2" |Uric Acid
|Blood serum or plasma
|Lithium heparin
|
|
|-
|Urine, 24 hour
|
|
|
|-
|Urinalysis
|Urine, first morning midstream clean-catch preferred
|
|Fresh samples <2h old
|
|-
|
|
|
|
|
|}
Special Samples:

* Keep on ice
** Blood gases
** Ammonia
* Protect from light
** Bilirubin
** Vitamin B12

== Lab Test Reference Intervals ==
{| class="wikitable"
|+
!Test
!Reference Interval
!↑ Conditions
!↓ Conditions
!Interferences
!Notes
|-
|Sodium
|135 - 145 mmol/L
|Hypernatremia
|
|
|
|-
|Potassium
|3.5 - 5.0 mmol/L
|
|
|
* ↑↑↑ Hemolysis
|
|-
|Chloride
|
|
|
|
|
|-
|Bicarbonate
|
|
|
|
|
|-
|Anion Gap
|10 - 20 mmol/L
|
* Ketoacidosis (diabetes, starvation)
* Renal failure
* Lactic acidosis
* Hypernatremia
* Poisoning (methanol, ethanol, ethylene glycol, salicylates)
|Rare

* Hypoalbuminemia
* Severe hypercalcemia
|
|
|-
|pH
|
|
|
|
|
|-
|pO<sub>2</sub>
|
|
|
|
|
|-
|pCO<sub>2</sub>
|
|
|
|
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|-
|[HCO<sub>3</sub><sup>-</sup>]
|
|
|
|
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|-
|
|
|
|
|
|
|-
|Glucose, fasting
|4.1 - 5.6 mmol/L
|
|
|
|
|-
|Glucose, random
|
|
|
|
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|-
|Total Bilirubin
|
|
|
|
|
|-
|Unconjugated Bilirubin
|
|
|
|
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|-
|Conjugated Bilirubin
|
|
|
|
|
|-
|eGFR
|>2.0 mL/s
|
|
|
|Preferred over creatinine clearance
|-
|Urine flow rate
|0.05 mL/s
|
|
|
|
|-
|Creatinine (serum)
|62 - 115 μmol/L (male)
53 - 97 μmol/L (female)
|
|
| rowspan="3" |
* ↑ Hemolysis
* ↓ Icterus
* ↓ Lipemia
* Ammonium heparin
* Non-specific chromogens
|
|-
|Creatinine (urine, 24h)
|9 - 18 mmol/d (male)
7 - 16 mmol/d (female)
|
|
|Inaccuracies may arise from improper urine measurement or tubular secretion.
|-
|Creatinine Clearance
|1.42 - 2.08 mL/s (male)
1.24 - 1.92 mL/s (female)
|
|
|<0.63 mL/s is markedly decreased
High serum creatinine may over-estimate CC.
|-
|[[Cardiac Testing#C-reactive protein|C-reactive protein]]
|<10 mg/L
|
|
|
|
|-
|
|
|
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|
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|}
Blood Gas Results
{| class="wikitable"
!Test
!Reference Interval
!Clinical Relevance
!Notes
|-
|Sodium
|135 - 145 mmol/L
|
|
|-
|Potassium
|3.5 - 5.0 mmol/L
|
|
|-
|Chloride
|
|
|
|-
|pH
|7.35 - 7.45
|
|
|-
|pO<sub>2</sub>
|
|
|
|-
|pCO<sub>2</sub>
|35 - 45 mmHg
|
|
|-
|[HCO<sub>3</sub><sup>-</sup>]
|21 - 28 mmol/L
|
|
|}
Heme -> bilirubin -> unconjugated bilirubin (transport via albumin) -> conjugated bili -> urobilinogen (in GI) -> urobilin excreted

Hepatic Jaundice

* ↑ AST, ALT, GGT 
* ALP N/↑
* ↑ Total, unconj., conj. bilirubin

Obstructive (post-hepatic) jaundice

* ↑↑ ALP and GGT
* ↑ Bilirubin
* ALT, AST vary

Enzymes

* ALT most liver specific
** Except alcoholic cirrhosis AST 2x ALT
* AST more general (liver, skeletal muscle, heart, RBCs)
* GGT sensitive to liver injury, but not specific (high in alcoholic liver cirrhosis)
* LD not specific
* ALP non-specific
* ↓ albumin, ↑ gamma globulins (IgG, IgM hepatitis; IgA alcoholic cirrhosis)
** Beta-gamma bridging

Pancreatitis

* Amylase
* Lipase (more specific than amylase)

Affected by HIL

* K<sup>+</sup>
* LD very sensitive!!! and unstable!!!
* AST
* Bilirubin
** ↓ Hemolysis
** ↑ Lipemia

Less Affected

* Na (dilutional effect)
* Cl (dilutional effect)
* ALP
* CK (gross hemolysis false ↑)

CSF Tubes

# Chemistry
# Microbiology
# Hematology
# Other (e.g., cytology)

Hashimoto = low T3,T4 and high TSH

Grave's = hyperthyroidism = excess T4, low TSH

Cushing's = high cortisol =

* High ACTH with ACTH-dependent (pituitary)
* Low ACTH with independent (adrenal cancer, etc.)
* Higher part of the body is high ACTH and dependent (pituitary); lower part of the body is low ACTH and independent (adrenal)

Cardiac Markers

* Myoglobin = earliest marker (but declines quickly)
* CK elevated in cardiac and skeletal disorders
** CK-MB/CK2 most specific isoenzyme for cardiac issues (but also skeletal)
* Cardiac troponin 1 is very cardiac-specific!
** High sensitivity cTnI used for investigating heart attacks
** Detectable quickly (3-12 hours), and remain elevated >1 week
* NT-proBNP elevated in heart failure
* CRP acute marker of inflammation, can help evaluate risk for CVD