The blood sample is sent to a lab for analysis. What you can expectĭuring the BUN test, a member of your health care team takes a sample of blood by inserting a needle into a vein in your arm. Your doctor will give you specific instructions. If your blood sample will be used for additional tests, you may need to fast for a certain amount of time before the test. If your blood sample is being tested only for BUN, you can eat and drink normally before the test. The GFR estimates the percentage of kidney function you have. To do this, you may have a blood sample taken to calculate your estimated glomerular filtration rate (GFR). Your doctor may also test how well your kidneys are removing waste from the blood. High levels of creatinine in your blood may be a sign of kidney damage. Creatinine is another waste product that healthy kidneys filter out of your body through urine. If kidney problems are the main concern, the creatinine levels in your blood will likely also be measured when your blood is tested for urea nitrogen levels. 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 help determine the effectiveness of dialysis treatment if you're receiving hemodialysis or peritoneal dialysis.If your kidney function needs to be evaluated, especially if you have a chronic condition such as diabetes or high blood pressure.

If your doctor suspects that you have kidney disease or damage.The filtered waste products leave your body through urine.Ī BUN test can reveal whether your urea nitrogen levels are higher than normal, suggesting that your kidneys may not be working properly.Healthy kidneys filter urea and remove other waste products from your blood.The urea travels from your liver to your kidneys through your bloodstream.The nitrogen combines with other elements, such as carbon, hydrogen and oxygen, to form urea, which is a chemical waste product.Your liver produces ammonia - which contains nitrogen - after it breaks down proteins used by your body's cells.

Normal bun range