How Many? A Dictionary of Units of Measurement
© Russ Rowlett and the University of North Carolina at Chapel Hill

Table of Contents
About the Dictionary
Using the Dictionary

SI Units for Clinical Data

The following table provides factors for converting conventional units to SI units for selected clinical data. Source: JAMA Author Instructions.


  • to convert from the conventional unit to the SI unit, multiply by the conversion factor;
  • to convert from the SI unit to the conventional unit, divide by the conversion factor.
SI Unit
Acetaminophen µg/mL 6.62 µmol/L
Acetoacetic acid mg/dL 0.098 mmol/L
Acetone mg/dL 0.172 mmol/L
Acid phosphatase units/L 1.0 U/L
Alanine mg/dL 112.2 µmol/L
Alanine aminotransferase (ALT) units/L 1.0 U/L
Albumin g/dL 10 g/L
Alcohol dehydrogenase units/L 1.0 U/L
Aldolase units/L 1.0 U/L
Aldosterone ng/dL 0.0277 nmol/L
Alkaline phosphatase units/L 1.0 U/L
Aluminum ng/mL 0.0371 µmol/L
Aminobutyric acid mg/dL 97 µmol/L
Amitriptyline ng/mL 3.61 nmol/L
Ammonia (as NH3) µg/dL 0.587 µmol/L
Amylase units/L 1.0 U/L
Androstenedione ng/dL 0.0349 nmol/L
Angiotensin I pg/mL 0.772 pmol/L
Angiotensin II pg/mL 0.957 pmol/L
Anion gap mEq/L 1.0 mmol/L
Antidiuretic hormone pg/mL 0.923 pmol/L
Antithrombin III mg/dL 10 mg/L
alpha1-Antitrypsin mg/dL 0.184 µmol/L
Apolipoprotein A mg/dL 0.01 g/L
Apolipoprotein B mg/dL 0.01 g/L
Arginine mg/dL 57.4 µmol/L
Asparagine mg/dL 75.7 µmol/L
Aspartate aminotransferase (AST) units/L 1.0 U/L
Bicarbonate mEq/L 1.0 mmol/L
Bilirubin mg/dL 17.1 µmol/L
Blood gases (arterial)      
     Paco2 mm Hg 1.0 mm Hg
     pH pH units 1.0 pH units
     Pao2 mm Hg 1.0 mm Hg
Bromide mg/dL 0.125 mmol/L
C-peptide ng/mL 0.333 nmol/L
C1 esterase inhibitor mg/dL 10 mg/L
C3 complement mg/dL 0.01 g/L
C4 complement mg/dL 0.01 g/L
Calcitonin pg/mL 1.0 ng/L
Calcium mg/dL 0.25 mmol/L
  mEq/L 0.50 mmol/L
Carbon dioxide mEq/L 1.0 mmol/L
Carboxyhemoglobin % of
hemoglobin saturation
0.01 Proportion of
hemoglobin saturation
Carotene µg/dL 0.0186 µmol/L
Ceruloplasmin mg/dL 10 mg/L
Chloride mEq/L 1.0 mmol/L
Cholesterol mg/dL 0.0259 mmol/L
Citrate mg/dL 52.05 µmol/L
Copper µg/dL 0.157 µmol/L
Coproporphyrins (urine) µg/24 hr 1.527 nmol/d
Corticotropin (ACTH) pg/mL 0.22 pmol/L
Cortisol µg/dL 27.59 nmol/L
Cotinine ng/mL 5.68 nmol/L
Creatine mg/dL 76.26 µmol/L
Creatine kinase (CK) units/L 1.0 U/L
Creatinine mg/dL 88.4 µmol/L
Creatinine clearance mL/min 0.0167 mL/s
Cyanide mg/L 23.24 µmol/L
Dehydroepiandrosterone (DHEA) ng/mL 3.47 nmol/L
Desipramine ng/mL 3.75 nmol/L
Diazepam µg/mL 3.512 µmol/L
Digoxin ng/mL 1.281 nmol/L
Epinephrine pg/mL 5.46 pmol/L
Erythrocyte sedimentation rate mm/h 1.0 mm/h
Estradiol pg/mL 3.671 pmol/L
Estriol ng/mL 3.467 nmol/L
Estrone ng/dL 37 pmol/L
Ethanol (ethyl alcohol) mg/dL 0.217 mmol/L
Ethylene glycol mg/L 16.11 µmol/L
Ferritin ng/mL 2.247 pmol/L
alpha -Fetoprotein ng/mL 1.0 µg/L
Fibrinogen mg/dL 0.0294 µmol/L
Fluoride µg/mL 52.6 µmol/L
Folate ng/mL 2.266 nmol/L
Follicle-stimulating hormone mIU/mL 1.0 IU/L
Fructose mg/dL 55.5 µmol/L
Galactose mg/dL 55.506 µmol/L
Glucagon pg/mL 1.0 ng/L
Glucose mg/dL 0.0555 mmol/L
Glutamine mg/dL 68.42 µmol/L
gamma -Glutamyltransferase (GGT) units/L 1.0 U/L
Glycated hemoglobin (glycosylated
hemoglobin A1, A1C)
% of total
0.01 Proportion of total
Glycerol (free) mg/dL 108.59 µmol/L
Glycine mg/dL 133.3 µmol/L
Haptoglobin mg/dL 0.10 µmol/L
Hematocrit % 0.01 Proportion
of 1.0
Hemoglobin (whole blood)
Mass concentration
g/dL 10.0
High-density lipoprotein cholesterol (HDL-C) mg/dL 0.0259 mmol/L
Histidine mg/dL 64.45 µmol/L
Homocysteine (total) mg/L 7.397 µmol/L
Human chorionic gonadotropin (HCG) mlU/mL 1.0 IU/L
Hydroxybutyric acid mg/dL 96.05 µmol/L
Hydroxyproline mg/dL 76.3 µmol/L
Immunoglobulin A (IgA) mg/dL 0.01 g/L
Immunoglobulin D (IgD) mg/dL 10 mg/L
Immunoglobulin E (IgE) mg/dL 10 mg/L
Immunoglobulin G (IgG) mg/dL 0.01 g/L
Immunoglobulin M (IgM) mg/dL 0.01 g/L
Insulin µIU/mL 6.945 pmol/L
Iron, total µg/dL 0.179 µmol/L
Iron binding capacity, total µg/dL 0.179 µmol/L
lsoleucine mg/dL 76.24 µmol/L
lsopropanol mg/L 0.0166 mmol/L
Lactate (lactic acid) mg/dL 0.111 mmol/L
Lactate dehydrogenase units/L 1 U/L
Lactate dehydrogenase
isoenzymes (LD1-LD5)
% 0.01 Proportion of 1.0
Lead µg/dL 0.0483 µmol/L
Leucine mg/dL 76.237 µmol/L
Lipase units/L 1.0 U/L
Lipids (total) mg/dL 0.01 g/L
Lipoprotein (a) mg/dL 0.0357 µmol/L
Lithium mEq/L 1.0 mmol/L
Low-density lipoprotein
cholesterol (LDL-C)
mg/dL 0.0259 mmol/L
Luteinizing hormone (LH, leutropin) IU/L 1.0 lU/L
Lysine mg/dL 68.5 µmol/L
Magnesium mg/dL 0.411 mmol/L
  mEq/L 0.50 mmol/L
Manganese ng/mL 18.2 nmol/L
Methanol mg/L 0.0312 mmol/L
Methemoglobin % of total
0.01 Proportion of total
Methionine mg/dL 67.02 µmol/L
Myoglobin µg/L 0.0571 nmol/L
Nicotine mg/L 6.164 µmol/L
Nitrogen, nonprotein mg/dL 0.714 mmol/L
Norepinephrine pg/mL 0.00591 nmol/L
Ornithine mg/dL 75.67 µmol/L
Osmolality mOsm/kg 1.0 mmol/kg
Osteocalcin µg/L 0.171 nmol/L
Oxalate mg/L 11.1 µmol/L
Parathyroid hormone pg/mL 1.0 ng/L
Phenobarbital mg/L 4.31 µmol/L
Phenylalanine mg/dL 60.54 µmol/L
Phenytoin µg/mL 3.96 µmol/L
Phosphorus mg/dL 0.323 mmol/L
Plasminogen mg/dL 0.113 µmol/L
  % 0.01 Proportion of 1.0
Plasminogen activator inhibitor mIU/mL 1.0 IU/L
Platelets (thrombocytes) x 103/µL 1.0 x 109/L
Potassium mEq/L 1.0 mmol/L
Pregnanediol (urine) mg/24h 3.12 µmol/d
Pregnanetriol (urine) mg/24 h 2.97 µmol/d
Progesterone ng/mL 3.18 nmol/L
Prolactin µg/L 43.478 pmol
Proline mg/dL 86.86 µmol/L
Prostate-specific antigen ng/mL 1.0 µg/L
Protein, total g/dL 10.0 g/L
Prothrombin g/L 13.889 µmol/L
Prothrombin time (protime, PT) s 1.0 s
Protoporphyrin, erythrocyte µg/dL 0.01777 µmol/L
Pyruvate mg/dL 113.6 µmol/L
Quinidine µg/mL 3.08 µmol/L
Red blood cell count x 106/µL 1.0 x 1012/L
Renin pg/mL 0.0237 pmol/L
Reticulocyte count % of RBCs 0.01 Proportion
of 1.0
Salicylate mg/L 0.00724 mmol/L
Serine mg/dL 95.2 µmol/L
Serotonin (5-hydroxytryptamine) ng/mL 0.00568 µmol/L
Sodium mEq/L 1.0 mmol/L
Somatomedin-C (insulinlike growth factor) ng/mL 0.131 nmol/L (coagulation factor II)
Somatostatin pg/mL 0.611 pmol/L
Taurine mg/dL 79.91 µmol/L
Testosterone ng/dL 0.0347 nmol/L
Theophylline µg/mL 5.55 µmol/L
Thiocyanate mg/L 17.2 µmol/L
Threonine mg/dL 83.95 µmol/L
Thyroglobulin ng/mL 1.0 µg/L
Thyrotropin (thyroid-stimulating
hormone, TSH)
mIU/L 1.0 mIU/L
Thyroxine, free (T4) ng/dL 12.87 pmol/L
Thyroxine, total (T4) µg/dL 12.87 nmol/L
Transferrin mg/dL 0.01 g/L
Triglycerides mg/dL 0.0113 mmol/L
     Free (T3) pg/dL 0.0154 pmol/L
     Resin uptake % 0.01 Proportion of 1.0
     Total (T3) ng/dL 0.0154 nmol/L
Troponin I (cardiac) ng/mL 1.0 µg/L
Troponin T (cardiac) ng/mL 1.0 µg/L
Tryptophan mg/dL 48.97 µmol/L
Tyrosine mg/dL 55.19 µmol/L
Urea nitrogen mg/dL 0.357 mmol/L
Uric acid mg/dL 59.48 µmol/L
Valine mg/dL 85.5 µmol/L
Vasoactive intestinal
pg/mL 1.0 ng/L
Vitamin A (retinol) µg/dL 0.0349 µmol/L
Vitamin B6 (pyridoxine) ng/mL 4.046 nmol/L
Vitamin B12 (cyanocobalamin) pg/mL 0.738 pmol/L
Vitamin C (ascorbic acid) mg/dL 56.78 µmol/L
Vitamin D      
    1,25-Dihydroxyvitamin D pg/mL 2.6 pmol/L
    25-Hydroxyvitamin D ng/mL 2.496 nmol/L
Vitamin E mg/dL 23.22 µmol/L
Vitamin K ng/mL 2.22 nmol/L
Warfarin µg/mL 3.247 µmol/L
White blood cell count x 103/µL 1.0 x 109/L
White blood cell differential
count (number fraction)
% 0.01 Proportion of 1.0
Zinc µg/dL 0.153 µmol/L

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June 13, 2001