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Urea Nitrogen Clearance (Urine)

Does this test have other names?

Urine urea nitrogen

What is this test?

This test measures the amount of urea nitrogen in your urine.

Urea nitrogen is a waste product made when your liver breaks down protein. It's carried in your blood, filtered out by your kidneys, and removed from your body in your urine. If your liver isn't healthy, it may not break down proteins the way it should, and if your kidneys aren't healthy, they may not correctly filter urea. Either of these problems can lead to changes in the amount of urea nitrogen in your body.

If you don't have enough fluid in your body (dehydration), you may have extra urea in your blood because you aren't passing much urine.

Why do I need this test?

You may have this test if your healthcare provider wants to find out how healthy your kidneys are or wants to see if your medical treatment is working.

You may also have this test to look at your protein balance.

What other tests might I have along with this test?

You may have blood tests, usually within 48 hours of this test. These tests may include:

  • Blood creatinine

  • Blood protein-to-creatinine

  • Blood albumin-to-creatinine ratio

You may also have a kidney X-ray or a kidney biopsy. For a biopsy, a tiny piece of your kidney tissue is removed and checked with a microscope.

What do my test results mean?

Test results may vary depending on your age, gender, health history, and other things. Your test results may be different depending on the lab used. They may not mean you have a problem. Ask your healthcare provider what your test results mean for you.

Results are given in grams per 24 hours. A normal range is about 12 to 20 grams/24 hours.

Lower levels may mean that you don't have enough protein in your diet or that you have kidney problems.

Higher levels may mean that you are getting too much protein in your diet, or your body is breaking down too much protein.

How is this test done?

This test needs a 24-hour urine sample. For this sample, you must collect all of your urine for 24 hours. Empty your bladder completely first thing in the morning without collecting it. Note the time. Then collect your urine every time you go to the bathroom over the next 24 hours in a container that your healthcare provider or the lab gives you.

Does this test pose any risks?

This test poses no known risks.

What might affect my test results?

Certain medicines can affect your results.

How do I get ready for this test?

You don't need to prepare for this test. But be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illegal drugs you may use. 

Online Medical Reviewer: Chad Haldeman-Englert MD
Online Medical Reviewer: Raymond Turley Jr PA-C
Online Medical Reviewer: Tara Novick BSN MSN
Date Last Reviewed: 10/1/2022
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