BUN

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Blood urea nitrogen

7 - 20 mg/dL. Note that normal values may vary among different laboratories.

Higher-than-normal levels may be due to:

• Congestive heart failure
• Excessive protein levels in the gastrointestinal tract
• Gastrointestinal bleeding
• Hypovolemia
• Heart attack
• Kidney disease, including glomerulonephritis, pyelonephritis, and acute tubular necrosis
• Kidney failure
• Shock
• Urinary tract obstruction

Lower-than-normal levels may be due to:

• Liver failure
• Low protein diet
• Malnutrition
• Over-hydration

Additional conditions under which the test may be done include:

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• Acute nephritic syndrome
• Alport syndrome
• Atheroembolic kidney disease
• Dementia due to metabolic causes
• Diabetic nephropathy/sclerosis
• Digitalis toxicity
• Epilepsy
• Generalized tonic-clonic seizure
• Goodpasture syndrome
• Hemolytic-uremic syndrome (HUS)
• Hepatokidney syndrome
• Interstitial nephritis
• Lupus nephritis
• Malignant hypertension (arteriolar nephrosclerosis)
• Medullary cystic kidney disease
• Membranoproliferative GN I
• Membranoproliferative GN II
• Type 2 diabetes
• Prerenal azotemia
• Primary amyloidosis
• Secondary systemic amyloidosis
• Wilms' tumor

Review Date: 05/13/2009
Reviewed By: 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.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org).