BUN:Creatinine Ratio (BCR)

Determines the probable cause of acute renal failure


The Blood urea nitrogen (BUN): Creatinine Ratio (BCR) is a renal function indicator, commonly used to determine the potential cause of acute renal failure (ARF).

BUN and creatinine are two metabolites steadily produced in the body. BUN is filtered in the nephrons and then reabsorbed in the blood, whereas creatinine is filtered and then secreted in the lumen. Thus, a healthy individual typically has serum BUN levels higher than serum creatinine levels. A measurable increase in the serum creatinine levels in hospitalized patients is indicative of ARF. Differentiating ARF into 3 categories (prerenal, intrinsic renal, and postrenal failure) is of significant clinical utility.

BCR between 10 and 20 is considered a normal value or may be suggestive of a post-renal cause of ARF. High BCR (>20) may be suggestive of a pre-renal cause of AFR. Low BCR (<10) may be suggestive of an intrinsic renal cause of AFR.


Harrison's Principles of Internal Medicine, 20th Edition.

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1. BUN

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