Your body creates ammonia when it breaks down protein from foods. Ammonia contains nitrogen, which mixes with other elements in your body, including carbon, hydrogen, and oxygen to form urea. Urea is a waste product that is 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. Additionally, it can help diagnose whether you have a problem with protein digestion or absorption from the gut.
Your doctor will usually 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 nitrogen 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
The urine urea nitrogen test involves analyzing urine samples that you collect during a specified 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.
A normal urea level in the urine is 12 to 20 grams over 24 hours.
Low levels of urea in the urine may suggest:
- too little protein in the diet
- kidney disease
High levels of urea in the urine may suggest:
- too much protein in the diet
- excessive protein breakdown in the body
Your doctor will contact you to go over your results once your urine samples have been analyzed. They may need to order more tests or physical exams before they are able to give you a diagnosis.
Medically Reviewed by: Steve Kim, MD
Published By: Healthline Networks, Inc.