BUN

What is BUN?

The BUN (Blood urea Nitrogen) test may be used to evaluate kidney function to detect kidney disease or monitor individuals already diagnosed with kidney disease. When the liver metabolizes proteins, it forms a waste product called urea. The urea is then released into the blood until it reaches the kidneys. There, it is filtered out of the blood into the urine. This process is ongoing and that's why there's always a small amount of urea nitrogen in our blood. Our blood levels rise, abnormally, if the kidneys are damaged or not functioning properly; as a result, they cannot filter out waste products, such as urea, causing urea nitrogen blood levels to increase.

Why take a BUN Test?

This test is commonly ordered during a routine medical exam, as well as other kidney function tests. It may be also be ordered with a Creatinine test, when someone is experiencing signs or symptoms of a kidney disease. The BUN test is indicated if you have signs and symptoms of any kidney dysfunction such as fatigue, swelling or puffiness around the eyes or the face, wrists, abdomen, thighs or even ankles. Other signs include a foaming bloody urine, high blood pressure, mid back pain or problems urinating.

Those whose blood creatinine levels and BUN levels are not within the normal ranges, will need to keep repeating the tests routinely as a way of monitoring for a kidney dysfunction.

What can cause BUN levels to rise?

Diets, that are high in protein, may lead to elevated levels of BUN, while diets that are very low in proteins can lead to abnormally low levels. Keep in mind that many drugs can increase your blood urea nitrogen levels, these include chloramphenicol and streptomycin. You need to inform your health care giver of these medications to have a better diagnosis. Pregnant women may also have either a decreased or an increased level of BUN.

What your BUN Test Results mean?

Normal BUN levels differ with age. Normal childhood levels should be 5 to 18 mg/dL and adults levels 8 to 20 mg/dL.

Where can I get a BUN test near me?

Please use our Lab Locator to find find a convenient testing location.

Reviewed By: Dr. Kurt Kloss, MD
Last Reviewed Date: May 24, 2019