Understanding Your Laboratory Test: Purpose, Sample Collection, and Results
A test that measures the amount of urea nitrogen in your urine collected over 24 hours to evaluate kidney function and protein metabolism.
{"This test measures how much urea nitrogen your kidneys filter from your blood in 24 hours","Urea is a waste product formed when your body breaks down protein","You will need to collect all urine produced in a 24-hour period","Results help doctors assess kidney function and protein intake","Abnormal results may indicate kidney disease or other metabolic conditions"}
Key facts at a glance
- LOINC
- 3096-5
- Short code
- UUN24
- Synonyms
- UUN 24h Ur-mRate
- Category
- chemistry
- Sample
- urine
- Container
- 24-hour urine container with or without preservative (typically boric acid or toluene)
- Units
- not specified
- Ref low
- 12
- Ref high
- 20
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–100 years
- Method
- Enzymatic method (urease) or Colorimetric method (Diacetyl monoxime)
- CPT
- 84540
- SNOMED
- 365761006
- Specimen volume
- Complete 24-hour collection (typically 1000-2000 mL total volume)
- Stability
- 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, and what does it measure? This laboratory test analyzes a patient sample to provide information about health, disease, or how well a treatment may be working.
The 24-hour urine urea nitrogen test measures the amount of urea nitrogen excreted in your urine over a 24-hour period. Urea is a waste product that forms when your liver breaks down protein from the foods you eat. Your kidneys normally 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.
Why is this test ordered? Your healthcare professional may order it to check for a medical condition, investigate symptoms, monitor an existing illness, assess treatment, or support another diagnostic decision.
Your doctor may order this test to evaluate kidney function, monitor kidney disease progression, assess protein intake or malnutrition, or investigate conditions affecting protein metabolism. It may also be used to monitor patients on dialysis or those with certain liver diseases.
How is the sample collected? Depending on the test, a trained healthcare professional may collect blood, urine, saliva, stool, or another specimen using standard procedures designed to keep you safe and maintain sample quality.
You will receive a special container from your healthcare provider. On the morning of the collection day, urinate into the toilet as usual when you wake up. After that, every time you urinate for the next 24 hours, collect the urine in the provided container. Keep the container refrigerated or in a cool place. Return the complete collection to the lab as instructed, even if you missed one collection during the 24-hour period.
What do the results mean? Results are interpreted using the laboratory’s reference range, your symptoms, medical history, and other findings; an abnormal value does not always mean that you have a disease.
Normal 24-hour urine urea nitrogen levels typically range from 12 to 20 grams per day, though reference ranges may vary by laboratory. Higher than normal levels may indicate high protein intake, excessive protein breakdown (catabolism), or kidney dysfunction. 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.
Reference range
12-20 g/24 hnot specified
Complete 24-hour urine collection required; no fasting or special diet needed (protein intake affects results)
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated urine urea nitrogen levels can indicate conditions such as excessive dietary protein intake, catabolic states (severe infections, burns, trauma), or impaired kidney function where the kidneys cannot properly filter waste. Decreased levels may suggest kidney disease, liver disease, malnutrition, or pregnancy. This test is particularly valuable for patients with chronic kidney disease to monitor protein intake and kidney function, and for evaluating the effectiveness of dialysis treatment.
Frequently asked questions
Do I need to fast before this test?
What happens if I miss collecting urine during the 24-hour period?
Can I exercise during the collection period?
Should I continue taking my medications during the collection?
How long does it take to get results?
Sources
- 1
- 2
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