BLOOD UREA NITROGEN

A blood urea nitrogen (BUN) test measures the amount of urea nitrogen in your blood, which can help diagnose or monitor kidney disease. Urea nitrogen is a waste product that your body produces when it breaks down protein, and healthy kidneys filter it out of your blood. A higher than normal BUN level may indicate that your kidneys aren't working well.

Normal range

Adults

7–20 milligrams per deciliter (mg/dL)

The normal range can vary depending on age and other health conditions.

When to get a BUN test

Reason

Kidney problems

You have or are at risk for a kidney problem

Kidney disease symptoms

You have symptoms of later stage kidney disease, such as needing to urinate more often or less often than usual, or itching

What to consider

Details

Medications

Some prescription drugs, over-the-counter medications, and/or dietary supplements can affect a BUN test.

Preparation

You may need to modify your medication schedule before the test.

Other tests

If BUN is being tested with other measurements, such as in a BMP or CMP, you may need to fast for eight to 12 hours before the blood draw.

To reduce your BUN levels, you can limit high-protein foods such as meats and dairy products. You can also try a diet low in protein