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.
Current as of: November 14, 2014
Author: Healthwise Staff
Medical Review: E. Gregory Thompson, MD - Internal Medicine & Brian D. O'Brien, MD - Internal Medicine & Michael Mallea, MD - Nephrology
Public health alerts include information about outbreaks, advisories and product recalls. Click on the links below to read the most recent alerts, or visit our Public Health Alerts web page.
If you are looking for health services in your community, you can use our directory to FIND hospitals, clinics, and other resources.
To learn more, visit Healthwise.org
© 1995-2015 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.
If you or someone in your care has chest pains, difficulty breathing, or severe bleeding, it could be life-threatening. Call 9-1-1 or the local emergency number immediately. If you are concerned about a possible poisoning or exposure to a toxic substance, call Poison Control now at 1-800-567-8911.