Understanding Your Laboratory Test and What the Results May Mean

This test examines a sample from your body to look for information that can help your healthcare professional evaluate your health, identify possible problems, or monitor an existing condition.

The urine urea nitrogen (UUN) test measures how much urea nitrogen is present in your urine over a specific period. Urea nitrogen is a waste product that forms when your body breaks down protein. Normally, your kidneys filter this waste from your blood and excrete it in urine. This test helps doctors understand how well your kidneys are performing this essential function.

Your healthcare professional may recommend this test to investigate symptoms, screen for a health condition, confirm or rule out a diagnosis, assess treatment, or track changes in your health over time.

Your doctor may order this test to: evaluate how well your kidneys are working, monitor existing kidney disease or damage, check if your body is properly breaking down protein, assess the effectiveness of dialysis or kidney treatments, or investigate unexplained changes in urination patterns. It is particularly useful for people with kidney disease, those on dialysis, or patients with protein metabolism disorders.

The test is performed by collecting the required sample, such as blood, urine, saliva, or another specimen, and sending it to a laboratory for analysis. Follow any preparation instructions provided.

The test requires collecting all urine produced over a 24-hour period. You will receive a special container from your healthcare provider. On the day of collection, start by urinating into the toilet when you wake up, then collect all subsequent urine in the provided container for the next 24 hours. Keep the container refrigerated or in a cool place. Return the complete collection to your lab as instructed.

Results are interpreted using the laboratory's reference range and your medical history, symptoms, medications, and other findings. An abnormal result does not always mean disease, and a normal result does not rule out every problem.

Normal urine urea nitrogen levels typically range from 12 to 20 grams per 24 hours, though reference ranges may vary by laboratory. Higher than normal levels may indicate high protein intake, excessive protein breakdown (catabolism), kidney disease affecting filtration, or use of certain medications. Lower than normal levels may suggest low protein diet, kidney damage reducing filtration capacity, liver disease affecting urea production, or severe malnutrition.

Risks depend on the type of sample collected and the procedure used. Most routine tests have few risks, although you may briefly experience discomfort, bruising, lightheadedness, or minor irritation at the collection site.

This test involves only normal urine collection and carries no significant physical risks. However, it is important to collect all urine over the 24-hour period for accurate results. Inform your doctor about all medications, supplements, and dietary habits before the test, as these can affect results.