Blood urea nitrogen (BUN) test

← Back to Library

Top of the page

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 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: September 10, 2024

Author: Ignite Healthwise, LLC Staff

Clinical Review Board
All Ignite Healthwise, LLC education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.

This information does not replace the advice of a doctor. Ignite Healthwise, LLC, disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. Learn how we develop our content.

Explore the Full Health and Wellness Library

Looking for easy to understand information you can trust? The health and wellness content is created and reviewed by clinicians to ensure accuracy. We suggest you use this resource as research for conversations with your doctor or those you care about.

Explore the Library

Community and Health Events

We regularly host free events to help you stay informed, connected, and inspired. We offer local in-person gatherings and virtual sessions you can attend from the comfort of home. View our calendar for all upcoming events.

Explore all Events