Your Medical Test: A Patient Guide to What It Checks, How It Is Performed, What Results Mean, and Safety Information Before Your Appointment
A urine test that measures the amount of urea nitrogen, a waste product from protein breakdown, to evaluate kidney function and protein metabolism.
{"Urea nitrogen is a waste product filtered from blood by the kidneys","This test helps assess how well your kidneys are working","Results can indicate kidney disease, dehydration, or protein intake levels","A 24-hour urine collection is often required for accurate results","Abnormal results may require additional testing"}
Key facts at a glance
- LOINC
- 111399-2
- Short code
- UUN
- Synonyms
- UUN Msmt Ur
- Category
- chemistry
- Sample
- urine
- Container
- Urine container (24-hour collection jug for timed specimens)
- Units
- not specified
- Ref low
- 12
- Ref high
- 20
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–120 years
- Method
- Enzymatic (Urease)
- CPT
- 84540
- SNOMED
- 370156007
- Specimen volume
- 10 mL minimum
- Stability
- Room temperature: 24 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C): 30 days
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 24–48 hours
- Order
- routine
What is this test, what does it check in your body, and why might your doctor order it at this appointment?
The Urine Urea Nitrogen test measures the amount of urea nitrogen in your urine. Urea nitrogen is a waste product created when your body breaks down protein from foods and tissues. Normally, your kidneys filter urea nitrogen from your blood and excrete it in urine. This test helps doctors understand how efficiently your kidneys are removing this waste product from your body.
How is the test performed step by step, what may you feel during it, and how long will the appointment usually take?
For this test, you will typically need to collect all urine produced over a 24-hour period in a special container provided by your healthcare provider. During this collection period, follow these steps: collect all urine starting from the second morning void, keep the container refrigerated or on ice, and bring the complete collection to your lab or healthcare facility as instructed. Some tests may only require a single urine sample.
What do the results mean, how are normal, borderline, and abnormal findings explained, and what should you ask your care team?
High levels of urea nitrogen in urine may indicate high protein intake, excessive protein breakdown (catabolism), or certain kidney disorders. Low levels may suggest kidney disease, malnutrition, or low protein intake. Your doctor will interpret your results based on your overall health, diet, and other test results.
Are there any risks, side effects, or discomforts during or after the test, and what precautions should you discuss with your doctor?
This test involves only normal urine collection and carries no significant physical risks. However, it is important to collect the sample correctly to ensure accurate results. Follow all collection instructions carefully and inform your healthcare provider if you have any difficulties.
Reference range
12-20 g/24 hnot specified
24-hour urine collection required; maintain usual diet and fluid intake
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
The urine urea nitrogen test is primarily used to evaluate kidney function. By measuring how much urea nitrogen is excreted in urine compared to blood levels, doctors can determine if the kidneys are properly filtering waste products from the body.
This test also helps assess protein balance in the body. Since urea nitrogen is produced from protein metabolism, measuring its excretion can indicate whether a person is consuming too much or too little protein, and whether the body is in a state of catabolism (breaking down tissue) or proper protein utilization.
Additionally, the test can help distinguish between different types of kidney problems. For example, it may help identify prerenal azotemia (reduced blood flow to kidneys) versus intrinsic kidney disease, as the pattern of urea nitrogen excretion differs between these conditions.
Frequently asked questions
Do I need to fast before this test?
Can I take my regular medications?
How long does it take to get results?
What happens if my results are abnormal?
Is this test painful?
Sources
- 1
- 2
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy