Reading Laboratory Test Results

Reading Laboratory Test Results

About Laboratory Results

Laboratory test results are reported to your physician along with ‘reference ranges’ that assist in accurately assessing and interpreting the results of the testing. Every test is different, and each test needs to be viewed in the context of differences in test methodologies employed by the testing laboratory.

Other important considerations are differences in groups of individuals such as: children, women, men, age groups, the population norms in the country of testing, and racial and ethnic factors.

Testing laboratories establish these reference range values for most Blood tests so that 95% of healthy patients fall within that ‘normal’ range. This means that 5% of healthy patients fall outside of the ‘reference’ range, even though there may be nothing wrong with them at all! Therefore, an ‘abnormal’ Blood test result does not necessarily mean that there is something wrong with you.

Many non-illness related factors may have an impact on your blood test results. These include such things as the meals eaten or not eaten (fasting) in the 24 hours preceding the test, race, dietetic preference, age, sex, stress, menstrual cycle, physical exercise in the hours before testing, collection and/or handling of the specimen, non-prescription drugs (aspirin, cold medications, vitamins, etc.), prescription drugs, alcohol intake, and the quality of the sleep that you got on the night before the test, among others.

Any unusual or abnormal test results should be talked over with your physician, and/or other qualified health care professional. These talks should continue until you understand all that you need to know about the testing and the results.

Blood Test Normal Range


Test                                               Reference Range

Alcohol 0 mg/dL (more than 0.1 mg/dL normally indicates intoxication) (ethanol)
Ammonia 15 – 50 µg of nitrogen/dL
Amylase 53 – 123 units/L
Ascorbic Acid 0.4 – 1.5 mg/dL
Bicarbonate 18 – 23 mEq/L (carbon dioxide content)
Bilirubin Direct: up to 0.4 mg/dL
Total: up to 1.0 mg/dL
Blood Volume 8.5 – 9.1% of total body weight
Calcium 8.5 – 10.5 mg/dL (normally slightly higher in children)
Carbon Dioxide Pressure 35 – 45 mm Hg
Carbon Monoxide Less than 5% of total hemoglobin
CD4 Cell Count 500 – 1500 cells/µL
Ceruloplasmin 15 – 60 mg/dL
Chloride 98 – 106 mEq/L
Complete Blood Cell Count (CBC) Tests include: hemoglobin, hematocrit, mean corpuscular hemoglobin,
mean corpuscular hemoglobin concentration, mean corpuscular volume,
platelet count,white blood cell count (numbers for all below)
Copper Total: 70 – 150 µg/dL
Creatine Kinase (CK or CPK) Male: 38 – 174 units/L
Female: 96 – 140 units/L
Creatine Kinase Isoenzymes 5% MB or less
Creatinine 0.6 – 1.2 mg/dL
Electrolytes Test includes: calcium, chloride, magnesium, potassium, sodium (numbers below)
Erythrocyte Sedimentation Rate (ESR or Sed-Rate) Male: 1 – 13 mm/hr
Female: 1 – 20 mm/hr
Glucose Tested after fasting: 70 – 110 mg/dL
Hematocrit Male: 45 – 62%
Female: 37 – 48%
Hemoglobin Male: 13 – 18 gm/dL
Female: 12 – 16 gm/dL
Iron 60 – 160 µg/dL (normally higher in males)
Iron-binding Capacity 250 – 460 µg/dL
Lactate (lactic acid) Venous: 4.5 – 19.8 mg/dL
Arterial: 4.5 – 14.4 mg/dL
Lactic Dehydrogenase 50 – 150 units/L
Lead 40 µg/dL or less (normally much lower in children)
Lipase 10 – 150 units/L
Zinc   B-Zn 70 – 102 µmol/L
   Cholesterol Less than 225 mg/dL (for age 40-49 yr; increases with age)
   Triglycerides 10 – 29 years 53 – 104 mg/dL
30 – 39 years 55 – 115 mg/dL
40 – 49 years 66 – 139 mg/dL
50 – 59 years 75 – 163 mg/dL
60 – 69 years 78 – 158 mg/dL
   >  70 years 83 – 141 mg/dL
Liver Function Tests Tests include bilirubin (total), phosphatase (alkaline), protein (total and albumin),transaminases (alanine and aspartate), prothrombin (PTT)
Magnesium 1.5 – 2.0 mEq/L
Mean CorpuscularHemoglobin (MCH) 27 – 32 pg/cell
Mean Corpuscular HemoglobinConcentration (MCHC) 32 – 36% hemoglobin/cell
Mean Corpuscular Volume (MCV) 76 – 100 cu µm
Osmolality 280 – 296 mOsm/kg water
Oxygen Pressure 83 – 100 mm Hg
Oxygen Saturation (arterial) 96 – 100%
Phosphatase, Prostatic 0 – 3 units/dL (Bodansky units) (acid)
Phosphatase 50 – 160 units/L (normally higher in infants and adolescents) (alkaline)
Phosphorus 3.0 – 4.5 mg/dL (inorganic)
Platelet Count 150,000 – 350,000/mL
Potassium 3.5 – 5.0 mEq/L
Prostate-Specific Antigen (PSA) 0 – 4 ng/mL (likely higher with age)
   Total 6.0 – 8.4 gm/dL
   Albumin 3.5 – 5.0 gm/dL
   Globulin 2.3 – 3.5 gm/dL
Prothrombin (PTT) 25 – 41 sec
Pyruvic Acid 0.3 – 0.9 mg/dL
Red Blood Cell Count (RBC) 4.2 – 6.9 million/µL/cu mm
Sodium 135 – 145 mEq/L
Thyroid-Stimulating Hormone (TSH) 0.5 – 6.0 µ units/mL
   Alanine (ALT) 1 – 21 units/L
   Aspartate (AST) 7 – 27 units/L
Urea Nitrogen (BUN) 7 – 18 mg/dL
BUN/Creatinine Ratio 5 – 35
Uric Acid Male 2.1 to 8.5 mg/dL (likely higher with age)
Female 2.0 to 7.0 mg/dL (likely higher with age)
Vitamin A 30 – 65 µg/dL
White Blood Cell Count (WBC) 4,300 – 10,800 cells/µL/cu mm


Urine Tests

Creatinine – is a measure of kidney functions to determine how dilute or concentrated a urine sample is. The creatinine has to be below 20 mg/dl for the sample to be considered too dilute. Creatinine levels above the 20 mg/dl are considered acceptable.

Creatinine is found in all muscle tissue and originally begins as creatine. Creatine passes through the body in two ways. First is consumption as it is found in all types of meat. The second is production by the body. As muscles are broken down and rebuilt creatine is converted creatinine. Creatinine in high levels is toxic, and so the kidneys filter out the creatinine from the blood and pass it on to the bladder. Creatinine extraction from the blood is at a very constant rate and the level in the urine is constant varying only with the length between urinations. Therefore creatinine levels less than 20 mg/dl indicate a bladder which is continually being emptied in an attempt to pass a drug test.

Labs sometimes look at other constituents of urine with a ten-panel dipstick called a multistick. The ten tests on the multistick are:

1. Leukocytes
2. Nitrite
3. Urobilinogen
4. Protein
5. pH
6. Blood
7. Specific Gravity
8. Ketone
9. Bilirubin
10. Glucose

Kidney damage goes through stages that can be monitored with standard lab tests:

1. Microalbuminuria occurs when trace amounts of a protein called albumin begin to leak through the damaged filtering structures of the kidneys. The presence of microalbumin in the urine is often an early warning of kidney disease, but can also be present for other reasons. Normal values on this test are less than 15 to 30 mg/l. The important microalbumin test should be done at least yearly in those who have had diabetes for five years or longer.

The test will help those who have had diabetes a relatively short time but have already started to spill microalbumin. As kidney damage progresses, microalbumin spillage will rise above 200 mg/l and be followed by:

2. Proteinuria is the spillage of larger quantities of protein. A standard urinalysis will pick up this spillage (normal is less than 100-150 mg/day, depending on the lab). As damage progresses and protein levels reach about 2000-4000 mg/day, proteinuria is followed by:

3. A rising blood creatinine. Creatinine is a normal breakdown product from muscle which the kidneys cleanse from blood (a normal creatinine is 1.1-1.3 mg/dl or less, depending on the lab). As damaged kidneys have more trouble cleansing the blood, creatinine levels rise. After a gradual buildup, toxins in the blood reach a critical stage (usually at a creatinine level between 3 and 8).