A blood urea nitrogen (BUN) test measures the amount of nitrogen in your blood that comes from the waste product urea. Urea is formed when protein is broken down in your body. It is made in the liver and removed from your body in urine.
A BUN test is done to tell how well your kidneys are working. If your kidneys are not able to remove urea from the blood normally, your BUN level increases. Heart failure, dehydration, certain medicines, intestinal bleeding, or a diet high in protein also can increase your BUN level. Liver disease or damage can decrease your BUN level, because urea is made in the liver. A decreased BUN level can occur normally in the second or third trimester of pregnancy.
| Author: | Monica Rhodes |
| Medical Review: | E. Gregory Thompson, MD - Internal Medicine Tushar J. Vachharajani, MD, FASN, FACP - Nephrology |
| Last Updated: August 12, 2008 | |
© 1995-2012 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.
This information does not replace the advice of a doctor. Healthwise discalims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use.