Blood urea nitrogen
BUN stands for blood urea nitrogen. Urea nitrogen is what forms when protein breaks down.
A test can be done to measure the amount of urea nitrogen in the blood.
A blood sample is needed. For information on how this is done, see: Venipuncture
Many drugs affect BUN levels. Before having this test, make sure the health care provider knows which medications you are taking.
Drugs that can increase BUN measurements include:
Drugs that can decrease BUN measurements include:
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.
The BUN test is often done to check kidney function.
The normal result is generally 6 - 20 mg/dL.
Note: Normal values may vary among different labs. Talk to your doctor about 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.
Higher-than-normal levels may be due to:
Lower-than-normal levels may be due to:
Additional conditions under which the test may be done include:
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 are slight but may include:
For people with liver disease, the BUN level may be low even if the kidneys are normal.
Clarkson MR, Friedewald JJ, Eustace JA, Rabb H. Acute kidney injury. In: Brenner BM, eds. Brenner and Rector’s The Kidney. 8th ed. Philadelphia, Pa: Saunders Elsevier; 2008:chap 29.
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