An Explanation of Normal Lab Values
Part of just about any annual medical exam is to have lab work, the results of which doctors examine for abnormal or normal lab values. Over years, researchers have developed a scale of normal lab values to which doctors will compare results of a particular patient’s lab work. The comparison will be able to give the doctor an idea of the patient’s health as compared to the average.
There are different sets of values for men, women and children. This is, obviously, because the differences in body size and composition are variable.
A standard lab work up that is commonly ordered consists of a specific number of criteria. If the doctor is attempting to determine particular information, additional tests may be ordered that would indicate or dismiss certain conditions.
Albumin 3.2 - 5 g/dl
Alkaline phosphatase (Adults: 25-60) 33 - 131 IU/L
Adults > 61 yo: 51 - 153 IU/L
Ammonia 20 - 70 mcg/dl
Bilirubin, direct 0 - 0.3 mg/dl
Bilirubin, total 0.1 - 1.2 mg/dl
Blood Gases
Arterial Venous
pH 7.35 - 7.45 7.32 - 7.42
pCO2 35 - 45 38 - 52
pO2 70 - 100 28 - 48
HCO3 19 - 25 19 - 25
O2 Sat % 90 – 95 40 - 70
BUN 7 - 20 mg/dl
Complete blood count (CBC) Adults
Male Female
Hemoglobin (g/dl) 13.5 - 16.5 12.0 - 15.0
Hematocrit (%) 41 - 50 36 - 44
RBC's ( x 106 /ml) 4.5 - 5.5 4.0 - 4.9
RDW (RBC distribution width) < 14.5
MCV 80 - 100
MCH 26 - 34
MCHC % 31 - 37
Platelet count 100,000 to 450,000
Creatinine kinase (CK) isoenzymes
CK-BB 0%
CK-MB (cardiac) 0 - 3.9%
CK-MM 96 - 100%
Creatine phosphokinase (CPK) 8 - 150 IU/L
Creatinine (mg/dl) 0.5 - 1.4
Electrolytes
Calcium 8.8 - 10.3 mg/dL
Calcium, ionized 2.24 - 2.46 meq/L
Chloride 95 - 107 mEq/L
Magnesium 1.6 - 2.4 mEq/L
Phosphate 2.5 - 4.5 mg/dL
Potassium 3.5 - 5.2 mEq/L
Sodium 135 - 147 mEq/L
Ferritin (ng/ml) 3 - 300
Folate (ng/dl) 3.6 - 20
Glucose, fasting (mg/dl) 60 - 110
Glucose (2 hours postprandial)
(mg/dl) Up to 140
Hemoglobin A1c 6-8
Iron (mcg/dl) 65 - 150
Lactic acid (meq/L) 0.7 - 2.1
LDH (lactic dehydrogenase) 56 - 194 IU/L
Lipoproteins and triglycerides
Cholesterol, total < 200 mg/dl
HDL cholesterol 30 - 70 mg/dl
LDL cholesterol 65 - 180 mg/dl
Triglycerides 45 - 155 mg/dl (< 160)
Osmolality 289 - 308 mOsm/kg
SGOT (AST) < 35 IU/L (20-48)
SGPT (ALT) <35 IU/L
Thyroid Function tests
Free T3 2.3-4.2 pg/ml
Serum T3 70-200 ng/dl
Free T4 0.5-2.1 ng/dl
Serum T4 4.0-12.0 mcg/dl
TSH 0.25-4.30 microunits/ml
Total iron binding capacity (TIBC) 250 - 420 mcg/dl
Transferrin > 200 mg/dl
Uric acid (male) 2.0 - 8.0 mg/dl
(female) 2.0 - 7.5 mg/dl
WBC + differential
WBC (cells/ml) 4,500 - 10,000
Segmented neutrophils 54 - 62%
Band forms 3 - 5% (above 8% indicates left shift)
Basophils 0 - 1 (0 - 0.75%)
Eosinophils 0 - 3 (1 - 3%)
lymphocytes 24 - 44 (25 - 33%)
Monocytes 3 - 6 (3 - 7%)
Unless you have been to medical school, these terms and values likely mean little to you. What is more important than you understanding their meanings and implications is that your medical professional understands them. Using these values to determine a particular individual’s health status gives the doctor a starting point from which to work. These values are by no means steadfast, as each person’s readings may vary slightly to either end of the spectrum yet still be perfectly normal.