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BUN:Creatinine Ratio Helpful for Diagnosing Hypovolemia and GI Bleed

Figure: BUN, creatinine, hypovolemia, GI bleed

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The BUN:creatinine ratio is a helpful calculation. Traditional teaching states that hypovolemia should be considered if the ratio is higher than 20:1. A ratio of more than 30:1 should prompt concern for an upper gastrointestinal bleed (a likelihood ratio of 7.5) based on a systematic review. (JAMA. 2012;307[10]:1072; https://bit.ly/36e79VM.)

This makes sense because blood is digested to protein and is then metabolized to BUN in the urea cycle within the liver.

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Dr. Linis the founder, CEO, and editor-in-chief of Academic Life in Emergency Medicine (https://www.ALiEM.com) and a professor of emergency medicine at the University of California San Francisco with interests in health professions education and digital scholarship. Follow her on Instagram@MichelleLinMDand on Twitter@M_Lin.