Back
Print 

Blood Urea Nitrogen (BUN) Test: About Your Child's Test

Skip Navigation

Top of the page

Location of kidneys, with detail of the kidneys, ureter, bladder, and urethra

What is it?

A blood urea nitrogen (BUN) test measures the amount of nitrogen in your child's blood that comes from the waste product urea. Urea is made in the liver. It's passed out of your child's body in the urine. If your child's kidneys can't remove urea from the blood normally, the BUN level rises. Dehydration can also make your child's BUN level higher.

A BUN test may be done with a blood creatinine test. The level of creatinine in your child's blood also tells how well your child's kidneys are working. A high creatinine level may mean that your child's kidneys aren't working as they should. BUN and creatinine tests can be used together to find the BUN-to-creatinine ratio.

Why is this test done?

A BUN test is done to:

  • See if your child's kidneys are working normally.
  • See if your child's kidney disease is getting worse.
  • See if treatment of your child's kidney disease is working.
  • Check for severe dehydration. Dehydration generally causes BUN levels to rise more than creatinine levels. This causes a high BUN-to-creatinine ratio.

How do you prepare for the test?

Don't let your child eat a lot of meat or other protein in the 24 hours before the BUN test.

How is the test done?

A health professional uses a needle to take a blood sample, usually from the arm.

What happens after the test?

  • Your child will probably be able to go home right away.
  • Your child can go back to his or her usual activities right away.

Follow-up care is a key part of your child's treatment and safety. Be sure to make and go to all appointments, and call your doctor if your child is having problems. Ask your doctor when you can expect to have your child's test results.

Where can you learn more?

Go to http://www.healthwise.net/patientEd

Enter B190 in the search box to learn more about "Blood Urea Nitrogen (BUN) Test: About Your Child's Test".

Current as of: April 30, 2024

Author: Ignite Healthwise, LLC Staff

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

Current as of: April 30, 2024

Author: Ignite Healthwise, LLC Staff

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

The Health Encyclopedia contains general health information. Not all treatments or services described are covered benefits for Kaiser Permanente members or offered as services by Kaiser Permanente. For a list of covered benefits, please refer to your Evidence of Coverage or Summary Plan Description. For recommended treatments, please consult with your health care provider.