Chemistry Specimen Processing: Difference between revisions
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!Test | !Test | ||
!Reference Interval | !Reference Interval | ||
! | !↑ Conditions | ||
!↓ Conditions | |||
!Interferences | !Interferences | ||
!Notes | !Notes | ||
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|Sodium | |Sodium | ||
|135 - 145 mmol/L | |135 - 145 mmol/L | ||
|Hypernatremia | |||
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* ↑↑↑ Hemolysis | |||
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|Chloride | |Chloride | ||
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|Bicarbonate | |||
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|Anion Gap | |||
|10 - 20 mmol/L | |||
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* Ketoacidosis (diabetes, starvation) | |||
* Renal failure | |||
* Lactic acidosis | |||
* Hypernatremia | |||
* Poisoning (methanol, ethanol, ethylene glycol, salicylates) | |||
|Rare | |||
* Hypoalbuminemia | |||
* Severe hypercalcemia | |||
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|pH | |pH | ||
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|pO<sub>2</sub> | |pO<sub>2</sub> | ||
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|pCO<sub>2</sub> | |pCO<sub>2</sub> | ||
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|[HCO<sub>3</sub><sup>-</sup>] | |[HCO<sub>3</sub><sup>-</sup>] | ||
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|Glucose, fasting | |Glucose, fasting | ||
|4.1 - 5.6 mmol/L | |4.1 - 5.6 mmol/L | ||
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|Glucose, random | |Glucose, random | ||
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|Total Bilirubin | |Total Bilirubin | ||
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|Unconjugated Bilirubin | |Unconjugated Bilirubin | ||
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|Conjugated Bilirubin | |Conjugated Bilirubin | ||
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|eGFR | |eGFR | ||
|>2.0 mL/s | |>2.0 mL/s | ||
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|Urine flow rate | |Urine flow rate | ||
|0.05 mL/s | |0.05 mL/s | ||
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|62 - 115 μmol/L (male) | |62 - 115 μmol/L (male) | ||
53 - 97 μmol/L (female) | 53 - 97 μmol/L (female) | ||
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|9 - 18 mmol/d (male) | |9 - 18 mmol/d (male) | ||
7 - 16 mmol/d (female) | 7 - 16 mmol/d (female) | ||
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|Inaccuracies may arise from improper urine measurement or tubular secretion. | |Inaccuracies may arise from improper urine measurement or tubular secretion. | ||
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|1.42 - 2.08 mL/s (male) | |1.42 - 2.08 mL/s (male) | ||
1.24 - 1.92 mL/s (female) | 1.24 - 1.92 mL/s (female) | ||
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|<0.63 mL/s is markedly decreased | |<0.63 mL/s is markedly decreased | ||
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|[[Cardiac Testing#C-reactive protein|C-reactive protein]] | |[[Cardiac Testing#C-reactive protein|C-reactive protein]] | ||
|<10 mg/L | |<10 mg/L | ||
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Latest revision as of 11:15, 18 May 2025
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
| 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 | ||
| Glucose | Fasting | 4.1 - 5.6 mmol/L | ||
| Random | ||||
| Creatinine | Urine, 24 hour | |||
| Blood serum | Lithium heparin | |||
| Serum Iron | ||||
| Ferritin | ||||
| Total Iron Binding Capacity | ||||
| % Transferrin Saturation | 20-55% | |||
| 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 | ||
| 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
| Test | Reference Interval | ↑ Conditions | ↓ Conditions | Interferences | Notes |
|---|---|---|---|---|---|
| Sodium | 135 - 145 mmol/L | Hypernatremia | |||
| Potassium | 3.5 - 5.0 mmol/L |
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| Chloride | |||||
| Bicarbonate | |||||
| Anion Gap | 10 - 20 mmol/L |
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Rare
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| pH | |||||
| pO2 | |||||
| pCO2 | |||||
| [HCO3-] | |||||
| Glucose, fasting | 4.1 - 5.6 mmol/L | ||||
| Glucose, random | |||||
| Total Bilirubin | |||||
| Unconjugated Bilirubin | |||||
| 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) |
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| 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. | |||
| C-reactive protein | <10 mg/L | ||||
Blood Gas Results
| Test | Reference Interval | Clinical Relevance | Notes |
|---|---|---|---|
| Sodium | 135 - 145 mmol/L | ||
| Potassium | 3.5 - 5.0 mmol/L | ||
| Chloride | |||
| pH | 7.35 - 7.45 | ||
| pO2 | |||
| pCO2 | 35 - 45 mmHg | ||
| [HCO3-] | 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+
- 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