Skip to Content
Home > Wellness > Health Library > Blood Urea Nitrogen (BUN) Test
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
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
E. Gregory Thompson, MD - Internal Medicine & Michael Mallea, MD - Nephrology
How this information was developed to help you make better health decisions.
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.
Our interactive Decision Points guide you through making key health decisions by combining medical information with your personal information.
You'll find Decision Points to help you answer questions about:
Get started learning more about your health!
Our Interactive Tools can help you make smart decisions for a healthier life. You'll find personal calculators and tools for health and fitness, lifestyle checkups, and pregnancy.
Feeling under the weather?
Use our interactive symptom checker to evaluate your symptoms and determine appropriate action or treatment.