Examples of Conversions to Système International (SI) Units
| Component | System | Conventional U.S. Reference Intervals | Conventional U.S. Unit | Conversion Factor | SI Reference Intervals | SI Unit Symbol |
|---|---|---|---|---|---|---|
| Alanine aminotransferase (ALT) | Serum | |||||
| 10–40 | U/L | 0.01667 | 0.17–0.68 | μkat/L | |
| 7–35 | U/L | 0.01667 | 0.12–0.60 | μkat/L | |
| Albumin | Serum | 3.5–5.2 | g/dL | 10 | 35–52 | g/L |
| Aspartate aminotransferase (AST) | Serum | |||||
| 14–20 | U/L | 0.01667 | 0.23–0.33 | μkat/L | |
| 10–36 | U/L | 0.01667 | 0.17–0.60 | μkat/L | |
| Bilirubin | Serum | |||||
| 0–0.2 | mg/dL | 17.10 | 0–3.4 | μmol/L | |
| 0.3–1.0 | mg/dL | 17.10 | 5–17 | μmol/L | |
| Calcium, ionized | Serum | 4.65–5.28 | mg/dL | 0.2495 | 1.16–1.32 | mmol/L |
| Carbon dioxide, total | Serum | 23–30 | mEq/L | 1.00 | 23–30 | mmol/L |
| Chloride | Serum | 96–106 | mEq/L | 1.00 | 96–106 | mmol/L |
| Cholesterol | Serum | |||||
| <100 | mg/dL | 0.02586 | <2.6 | mmol/L | |
| <225 | mg/dL | 0.02586 | <5.80 | mmol/L | |
| <35–65 | mg/dL | 0.02586 | 0.91–1.68 | mmol/L | |
| <35–80 | mg/dL | 0.02586 | 0.91–2.07 | mmol/L | |
| Complete blood count | Blood | |||||
| Hematocrit | ||||||
| 42–52 | % | 0.01 | 0.42–0.52 | Proportion of 1 | |
| 36–48 | % | 0.01 | 0.36–0.48 | Proportion of 1 | |
| Red cell count | Blood | |||||
| 4.2–5.4 × 106 | /mm3 | 1 | 4.2–5.4 × 1012 | /L | |
| 3.6–5.0 × 106 | /mm3 | 1 | 3.6–5.0 × 1012 | /L | |
| 5.0–10.0 × 103 | /mm3 | 0.001 | 4.5–11.0 × 109 | /L | |
| 140–400 × 103 | /mm3 | 1 | 150–300 × 109 | /L | |
| Cortisol | Serum | |||||
| 5–23 | μg/dL | 27.59 | 138–635 | nmol/L | |
| 3–16 | μg/dL | 27.59 | 83–441 | nmol/L | |
| Creatine kinase (CK) | Serum | |||||
| 38–174 | U/L | 0.0167 | 0.63–2.90 | μkat/L | |
| 26–140 | U/L | 0.0167 | 0.46–2.38 | μkat/L | |
| Creatinine kinase isoenzyme, MB fraction | Serum | 0–6 | % | 1.00 | 0.00–0.06 | Proportion of 1 |
| Creatinine | Serum | |||||
| 0.9–1.3 | mg/dL | 88.40 | 80–115 | μmol/L | |
| 0.6–1.1 | mg/dL | 88.40 | 53–97 | μmol/L | |
| Digoxin, therapeutic | Serum | 0.5–2.0 | ng/mL | 1.281 | 0.6–2.6 | nmol/L |
| Erythrocyte indices | Blood | |||||
| Mean corpuscular volume (MCV) | 82–98 | mm3 | 1.00 | 82–98 | fL | |
| Mean corpuscular hemoglobin (MCH) | 26–34 | pg/cell | 0.062 | 1.61–2.11 | fmol/cell | |
| Mean corpuscular hemoglobin concentration (MCHC) | 32–36 | g/dL | 0.153 | 4.9–5.5 | mmol/L | |
| Ferritin | Serum | |||||
| 18–270 | ng/mL | 1.00 | 18–270 | μg/L | |
| 18–160 | ng/mL | 1.00 | 18–160 | μg/L | |
| Folate (folic acid) | Serum | 3–13 | ng/mL | 2.266 | 6.8–29.5 | nmol/L |
| Follicle-stimulating hormone (FSH) | Serum | |||||
| 1.24–7.8 | mIU/mL | 1.00 | 1.24–7.8 | IU/L | |
| 1.68–15 | mIU/mL | 1.00 | 1.68–15 | IU/L | |
| 21.9–56.6 | mIU/mL | 1.00 | 21.9–56.6 | IU/L | |
| 0.61–16.3 | mIU/mL | 1.00 | 0.61–16.3 | IU/L | |
| Gases, arterial | Blood | |||||
| >80 | mm Hg | 0.1333 | >10.6 | kPa | |
| 35–45 | mm Hg | 0.1333 | 4.6–5.9 | kPa | |
| Glucose, fasting | Serum | <100 | mg/dL | 0.0555 | <5.6 | mmol/L |
| Iron | Serum | |||||
| Serum | 70–175 | μg/dL | 0.1791 | 12.5–31.3 | μmol/L |
| 50–150 | μg/dL | 0.1791 | 8.9–26.8 | μmol/L | |
| 250–450 | μg/dL | 0.1791 | 44.8–76.1 | μmol/L | |
| Lactate dehydrogenase (LDH) | Serum | 140–280 | U/L | 0.0167 | 2.34–4.68 | μkat/L |
| Luteinizing hormone | Serum | |||||
| 1.42–15.4 | mIU/mL | 1.00 | 1.42–15.4 | IU/L | |
| 1.37–9.9 | mIU/mL | 1.00 | 1.37–9.9 | IU/L | |
| 1.09–9.2 | mIU/mL | 1.00 | 1.09–9.2 | IU/L | |
| Magnesium | Serum | 1.8–2.6 | mg/L | 0.4114 | 0.74–1.07 | mmol/L |
| Osmolality | Serum | 280–303 | mOsm/kg | 1.00 | 280–303 | mmol/kg |
| Osmolality, random | Urine | 50–1400 | mOsm/kg | 1.00 | 50–1400 | mmol/kg |
| Phenobarbital, therapeutic | Serum | 15–40 | μg/mL | 4.306 | 65–175 | μmol/L |
| Phenytoin, therapeutic | Serum | 10–20 | μg/mL | 3.964 | 40–80 | μmol/L |
| Phosphate (phosphorus, inorganic) | Serum | 2.7–4.5 | mg/dL | 0.3229 | 0.87–1.45 | mmol/L |
| Potassium | Serum | 3.5–5.2 | mEq/L g/mL | 1.00 | 3.5–5.2 | mmol/L |
| Sodium | Serum | 136–145 | mEq/L | 1.00 | 136–145 | mmol/L |
| Theophylline, therapeutic | Serum | 5–15 | μg/mL | 5.550 | 28–83 | μmol/L |
| Thyroid-stimulating hormone (TSH) | Serum | 0.45–4.5 | μU/mL | 1.00 | 0.45–4.5 | mU/L |
| Thyroxine, total (T4) | Serum | 5.4–11.5 | μg/dL | 12.87 | 57–148 | nmol/L |
| Triglycerides | Serum | <150 | mg/dL | 0.01129 | <1.70 | mmol/L |
| Triiodothyronine, total (T3) | Serum | 80–200 | ng/mL | 0.01536 | 1.2–3.1 | nmol/L |
| Urate (uric acid) | Serum | |||||
| 3.4–7.0 | mg/dL | 0.0595 | 0.020–0.041 | mmol/L | |
| 2.4–6.0 | mg/dL | 0.0595 | 0.014–0.036 | mmol/L | |
| Urea nitrogen | Serum | 6–20 | mg/dL | 0.3570 | 2.1–7.1 | mmol/L |
| Vitamin B12 | Serum | 250–1500 | pg/mL | 0.7378 | 206–1107 | pmol/L |
American Medical Association. (2020). Manual of style: A guide for authors and editors (11th ed.). Oxford University Press.