Why it's doneBy Mayo Clinic staff
You may need a blood urea nitrogen test:
- If your doctor suspects that you have kidney damage
- If your kidney function needs to be evaluated
- To help determine the effectiveness of dialysis treatment if you're receiving hemodialysis or peritoneal dialysis
- As part of a blood test group to help diagnose a number of other conditions, such as liver damage, urinary tract obstruction, congestive heart failure or gastrointestinal bleeding — although an abnormal BUN test result alone doesn't confirm any of these conditions
If kidney problems are the main concern, when your blood is tested for urea nitrogen levels, it's likely it will also be tested for creatinine levels. Creatinine is another waste product that healthy kidneys filter out of your body through urine. High levels of creatinine may be a sign of kidney damage.
To get the best indication of how well your kidneys are removing waste from the blood, you may have a blood sample taken to calculate your estimated glomerular filtration rate (eGFR). The eGFR estimates the percentage of kidney function you have left.
- The kidneys and how they work. National Kidney and Urologic Diseases Information Clearinghouse. http://kidney.niddk.nih.gov/kudiseases/pubs/yourkidneys/. Accessed May 30, 2013.
- BUN. Lab Tests Online. http://labtestsonline.org/understanding/analytes/bun/tab/test. Accessed June 8, 2013.
- Taal MW, et al. Brenner & Rector's The Kidney. 9th ed. Philadelphia, Pa.: Saunders Elsevier; 2011. http://www.mdconsult.com/books/about.do?about=true&eid=4-u1.0-B978-1-4160-6193-9..C2010-1-67932-1--TOP&isbn=978-1-4160-6193-9&uniqId=321553651-265. Accessed May 30, 2013.
- Inkler LA, et al. Assessment of kidney function. http://www.uptodate.com/home. Accessed May 30, 2013.
- Anderson CF (expert opinion). Mayo Clinic, Rochester, Minn. June 11, 2013.
- Castle EP (expert opinion). Mayo Clinic, Rochester, Minn. June 19, 2013.
- National Kidney Foundation. Tests to measure kidney function, damage and detect abnormalities. http://www.kidney.org/atoz/content/kidneytests.cfm. Accessed June 25, 2013.