Urea is a substance that is formed in the liver when the body breaks down protein. Urea then circulates in the blood in the form of urea nitrogen. A common blood test, the blood urea nitrogen (BUN) test reveals important information about how well your kidneys and liver are working. A BUN test measures the amount of urea nitrogen that's in your blood.
What’s The Normal Range of BUN?
Normal BUN levels are 5-18 mg/dL for children; 7-18 mg/dL for adults; and 8-20 mg/dL in the elderly.
Who Needs to Take It?
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.
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 (GFR). The GFR estimates the percentage of kidney function you have left.