A blood sample is needed. For information on how this is done, see: Venipuncture
How to prepare for the test
You should not eat or drink for 8 hours before the test.
How the test will feel
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the test is performed
This test can be used to evaluate kidney function, blood acid/base balance, and your levels of blood sugar, and electrolytes. Depending on which lab you use, a basic metabolic panel may also check your levels of calcium and a protein called albumin.
BUN: 7 to 20 mg/dL
CO2 (carbon dioxide): 20 to 29 mmol/L
Creatinine: 0.8 to 1.4 mg/dL
Glucose: 64 to 128 mg/dL
Serum chloride: 101 to 111 mmol/L
Serum potassium: 3.7 to 5.2 mEq/L
Serum sodium: 136 to 144 mEq/L
Key to abbreviations:
L = liter
dL = deciliter = 0.1 liter
mg = milligram
mmol = millimole
mEq = milliequivalents
Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.
What abnormal results mean
Abnormal results can be due to a variety of different medical conditions, including kidney failure, breathing problems, and diabetes-related complications. See the individual tests for detailed information:
Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
Fainting or feeling light-headed
Hematoma (blood accumulating under the skin)
Infection (a slight risk any time the skin is broken)
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.