BUN stands for blood urea nitrogen. Urea nitrogen is what forms when protein breaks down.
A test can be done to measure the amount of urea nitrogen in the blood.
A blood sample is needed. Most of the time blood is drawn from a vein located on the inside of the elbow or the back of the hand.
Many medicines can interfere with blood test results.
You may feel slight pain or a sting when the needle is inserted. You may also feel some throbbing at the site after the blood is drawn.
The BUN test is often done to check kidney function.
The normal result is generally 6 to 20 mg/dL.
Note: Normal values may vary among different labs. Talk to your provider about your specific test results.
The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.
Higher-than-normal level may be due to:
Lower-than-normal level may be due to:
For people with liver disease, the BUN level may be low, even if the kidneys are normal.
Reviewed By: Laura J. Martin, MD, MPH, ABIM Board Certified in Internal Medicine and Hospice and Palliative Medicine, Atlanta, GA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.