Laboratory Test: What This Test Measures, Why It Is Ordered, How to Prepare for Sample Collection, and What Results Can Mean

This test examines a sample to measure cells, chemicals, proteins, hormones, or other markers that can help your healthcare provider learn more about your current health and possible conditions.

The 24-hour urine urea nitrogen test measures the amount of urea nitrogen that your kidneys excrete in your urine over a 24-hour period. Urea is a waste product formed in your liver when protein is broken down. Normally, your kidneys filter urea from your blood and eliminate it through urine. This test helps doctors understand how well your kidneys are working and how your body is processing protein.

Your provider may order this test to screen for common health issues, investigate symptoms, monitor a known condition, check how well treatment is working, or establish a baseline for future comparison.

Your doctor may order this test to: evaluate kidney function, monitor kidney disease progression, assess protein intake and nutrition status, diagnose certain metabolic disorders, or monitor the effectiveness of kidney disease treatment. It provides important information about how efficiently your kidneys are removing waste products from your body.

Before the test, follow any instructions about eating, drinking, medicines, and activity. For sample collection, use the provided container, kit, or equipment and follow the steps your care team gives you.

Before the test, tell your doctor about all medications you take, as some can affect results. You may be asked to avoid certain foods or supplements for a period before the collection. For the 24-hour collection: on the start day, urinate into the toilet when you wake up, then collect all urine for the rest of the day and night in the provided container. On the second day, collect your first morning urine into the container as well. Keep the container refrigerated or in a cool place during collection. Return the container to the lab as instructed.

Results should be interpreted with your healthcare provider, who can compare them with reference ranges and consider your symptoms, medical history, medications, and other test results before explaining what they mean.

Normal 24-hour urine urea nitrogen values typically range from 12 to 20 grams per day, though this can vary based on your diet, muscle mass, and kidney function. Higher than normal levels may indicate high protein intake, excessive protein breakdown (catabolism), or kidney problems. Lower than normal levels may indicate kidney disease, malnutrition, or low protein intake. Your doctor will interpret your results based on your overall health, diet, and other test results.