Blood Urea Nitrogen

BUN (Blood Urea Nitrogen), BUN:Creatinine Ratio, Urea Nitrogen, Blood

Why It Is Done

A blood urea nitrogen (BUN) test is done to:

• See if your kidneys are working normally.
• See if your kidney disease is getting worse.
• See if treatment of your kidney disease is working.
• See if severe dehydration is present. Dehydration generally causes BUN levels to rise more than creatinine levels. This causes a high BUN-to-creatinine ratio. Kidney disease or blockage of the flow of urine from your kidney causes both BUN and creatinine levels to go up.

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Author:	Jan Nissl, RN, BS Sydney Youngerman-Cole, RN, BSN, RNC	Last Updated: November 21, 2006
Medical Review:	Patrice Burgess, MD - Family Medicine Andrew Swan, MD, CCFP, FCFP - Family Medicine
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