Urine Urea Nitrogen Test

Written by Amber Erickson Gabbey | Published on June 11, 2012
Medically Reviewed by George Krucik, MD

What Is the Urine Urea Nitrogen Test?

When your body breaks down protein, one of the waste products is ammonia, which contains nitrogen. The nitrogen mixes with other elements in your body, including carbon, hydrogen, and oxygen, and forms urea, which is a waste product. Urea is then excreted by the kidneys when you urinate.

The urine urea nitrogen test determines how much urea is in the urine to assess the amount of protein breakdown. The test can help determine how well the kidneys are functioning, and if your intake of protein is too high or low.

Purpose of a Urine Urea Nitrogen Test

Most commonly, your doctor will recommend a urea test to determine protein levels in the body. The test can determine how much protein you are eating, and if it is an adequate amount. In addition, your urea nitrogen levels may rise if you are going through heart failure or dehydration.

A common test for urea nitrogen is the blood urea nitrogen test, better known as BUN. This article refers to the urine urea nitrogen test, which is performed using a urine sample.

A urea test can also:

  • assess how well the kidneys are functioning
  • determine if you have kidney disease
  • monitor your kidney disease
  • help diagnose a number of diseases and disorders that may affect how your kidneys function

Urine Urea Nitrogen Test Process

The urine urea nitrogen test is performed by collecting a 24-hour urine sample urine sample. As the name suggests, you will need to collect a sample of all urine leaving the body over a 24-hour period.

It may seem awkward or uncomfortable to urinate into a cup, but no physical discomfort should occur. Follow your doctor’s orders about how to collect the sample. Generally, you will maintain normal eating and drinking habits during the collection phase.


Wash your hands carefully before and after collecting each sample. Also, make sure that you cap the containers tightly. Label and return the samples to the doctor as instructed. Samples need to be refrigerated during the 24-hour period.

On the first day of collection, you will not collect the urine first thing in the morning. Note the time, and then collect all urine for the remaining 24 hours.

Once collected, the urine is sent to the laboratory for analysis.

Understanding Your Test Results

A normal urea level in the urine is 12 to 20 grams over 24 hours.

Low levels of urea in the urine may suggest:

  • malnutrition
  • too little protein in the diet
  • kidney issues

High levels of urea in the urine may suggest:

  • too much protein in the diet
  • too much protein breakdown in the body
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