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Author Instructions

Système International (SI) Conversion Factors for Selected Laboratory Components

Updated September 28, 2001.

Conventional units of measure are preferred, with Système International (SI) units expressed secondarily (in parentheses). To convert values from conventional units to SI units, multiply by the conversion factor.

Component
Conventional
Unit 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)
(Dual report) 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

₁-Antitrypsin
(Dual report) 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
(Dual report) 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/mL 0.01 g/L

C4 complement mg/mL 0.01 g/L

Calcitonin pg/mL 1.0 ng/L

Calcium
(Dual report) 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
(Dual report) 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
(Dual report) mg/dL 88.4 µmol/L

Creatinine clearance
(Dual report) 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
(Dual report) ng/mL 1.281 nmol/L

Epinephrine pg/mL 5.46 pmol/L

Erythrocyte sedimentation rate mm/h 1.0 mm/h

Estradiol
(Dual report) 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

-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
(Dual report) mg/dL 0.0555 mmol/L

Glutamine mg/dL 68.42 µmol/L

-Glutamyltransferase (GGT) units/L 1.0 U/L

Glycated hemoglobin (glycosylated
hemoglobin A₁, A_1C) % of total
hemoglobin 0.01 Proportion
of total
hemoglobin

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

Hemoglobn (whole blood)
Mass concentration g/dL 10.0 g/L

High-density lipoprotein cholesterol (HDL-C)
(Dual report) 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
(Dual report) µg/dL 0.179 µmol/L

Iron binding capacity, total
(Dual report) 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
(Dual report) 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)
(Dual report) mg/dL 0.0259 mmol/L

Luteinizing hormone (LH, leutropin) IU/L 1.0 lU/L

Lysine mg/dL 68.5 µmol/L

Magnesium
(Dual report) 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
hemoglobin 0.01 Proportion
of total
hemoglobin

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
(Dual report) 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) ×10³/µL 1.0 ×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 ×10⁶/µL 1.0 ×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
(Dual report) 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)
(Dual report) ng/dL 12.87 pmol/L

Thyroxine, total (T₄)
(Dual report) µg/dL 12.87 nmol/L

Transferrin mg/dL 0.01 g/L

Triglycerides
(Dual report) mg/dL 0.0113 mmol/L

Triiodothyronine

     Free (T₃)
     (Dual report) pg/dL 0.0154 pmol/L

     Resin uptake % 0.01 Proportion
of 1.0

     Total (T₃)
     (Dual report) 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
(Dual report) mg/dL 0.357 mmol/L

Uric acid mg/dL 59.48 µmol/L

Valine mg/dL 85.5 µmol/L

Vasoactive intestinal
polypeptide 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 ×10³/µL 1.0 ×10⁹/L

White blood cell differential
count (number fraction) % 0.01 Proportion
of 1.0

Zinc µg/dL 0.153 µmol/L

The information in this table is from the following sources:

Iverson C, Flanagin A, Fontanarosa PB, et al. American Medical Association Manual of Style: A Guide for Authors and Editors. 9th ed. Baltimore, Md: Williams & Wilkins; 1998.

Tietz NW, ed. Clinical Guide to Laboratory Tests. 3rd ed. Philadelphia, Pa: WB Saunders Co; 1995.

Jacobs DS, Demott WR, Grady HJ, et al, eds. Laboratory Test Handbook. 4th ed. Hudson, Ohio: Lexi-Comp Inc; 1996.

Young DS, Huth EJ. SI Units for Clinical Measurement. Philadelphia, Pa: American College of Physicians; 1998.

Kratz A, Lewandrowski KB. Normal reference laboratory values. N Engl J Med. 1998;339:1036-1042.

Dual Report
Because of the continued use of conventional units in many laboratories in the United States, some of the more common analytes currently are dual reported (identified as "Dual report" in this table), with the SI value and unit listed first, followed by the conventional value and unit. Analytes with a 1-to-1 conversion between SI and conventional units or with a conversion factor that is a multiple of 10 usually are not dual reported. Information on how to convert from SI units to conventional units may be given in the text, in a table footnote, or in a figure legend (eg, to convert ethanol from millimoles per liter to milligrams per deciliter, divide millimoles per liter by 0.217).

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