BUN - blood test - Overview

Alternative Names

Blood urea nitrogen

Definition of BUN - blood test:

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.

How the test is performed:

A blood sample is needed. For information on how this is done, see: Venipuncture

How to prepare for the test:

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:

Allopurinol
Aminoglycoside antibiotics
Amphotericin B
Aspirin (high doses)
Bacitracin
Carbamazepine
Cephalosporins
Chloral hydrate
Cisplatin
Colistin
Furosemide
Guanethidine
Indomethacin
Methicillin
Methotrexate
Methyldopa
Neomycin
Penicillamine
Polymyxin B
Probenecid
Propranolol
Rifampin
Spironolactone
Tetracyclines
Thiazide diuretics
Triamterene
Vancomycin

Drugs that can decrease BUN measurements include:

Chloramphenicol
Streptomycin

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:

The BUN test is often done to check kidney function.

Reviewed last on: 5/30/2011
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School, Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

References

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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