Medical Test Overview: What It Is, How It Is Performed, and How to Prepare
A 24-hour urine ammonia test measures the amount of ammonia in your urine to help evaluate kidney function and acid-base balance.
{"This test measures ammonia, a waste product from protein breakdown, in a 24-hour urine collection","It helps doctors assess kidney function and diagnose conditions like renal tubular acidosis","Proper 24-hour urine collection is essential for accurate results","Results may be affected by diet, medications, and certain medical conditions"}
Key facts at a glance
- LOINC
- 25850-9
- Short code
- Ammonia 24h Ur-sCnc
- Synonyms
- Ammonia 24h Ur-sCnc
- Category
- chemistry
- Sample
- urine
- Container
- Sterile urine container
- Units
- N/A
- Critical range
- — – 200 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Specimen volume
- 10 mL
- Stability
- Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
This test is a diagnostic procedure that helps your healthcare provider assess how well your body is functioning and look for signs of illness. The results can support a diagnosis, guide treatment decisions, or be used to monitor an ongoing condition over time. Your doctor will interpret the findings together with your medical history, symptoms, and any other tests you have had.
The 24-hour urine ammonia test measures how much ammonia your kidneys excrete in a 24-hour period. Ammonia is a waste product created when your body breaks down proteins. Your kidneys normally filter ammonia from your blood and excrete it in urine to help maintain the body's acid-base balance.
The procedure is usually quick and is carried out by a trained member of your care team in a clinical setting. Depending on the type of test, a small sample of blood, urine, or other body tissue may be collected. You may feel a brief pinch or mild discomfort during sample collection, but most people tolerate the process well and can return to their normal activities right away.
For a 24-hour urine collection, you will receive a special container from your healthcare provider. Starting on the morning of the collection day, you will begin collecting all urine you produce over 24 hours. This includes the first urine of the morning on day one (which you should discard) and all urine produced throughout the day and night, including the first urine on the morning of day two. The container should be kept refrigerated or on ice during the collection period.
Your healthcare provider will give you specific instructions before the test. You may be asked to fast for a certain number of hours, avoid certain foods, drinks, or medications, and drink plenty of water beforehand. Wear comfortable clothing, and tell your care team about any medications, supplements, or allergies you have. Following these preparation steps carefully helps ensure accurate results.
Your healthcare provider may ask you to avoid certain foods, medications, or supplements before the test, as these can affect ammonia levels. It is important to inform your doctor about all medications you are taking. You should also avoid strenuous exercise before and during the collection, as exercise can affect test results. Follow any specific instructions provided by your healthcare team.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
The 24-hour urine ammonia test is primarily used to evaluate kidney function, particularly the kidney's ability to excrete acid and maintain acid-base balance. It is commonly used to diagnose and monitor renal tubular acidosis (RTA), a condition where the kidneys fail to properly acidify urine. The test can also help detect certain urinary tract infections, assess liver disease severity, and evaluate metabolic disorders. Abnormal ammonia levels in urine may indicate kidney problems, liver disease, or metabolic conditions that affect acid handling in the body.
Frequently asked questions
Why do I need to collect urine for 24 hours?
What happens if I miss some urine during the 24-hour collection?
Can I take my regular medications during the collection?
What do high ammonia levels in urine mean?
Is the 24-hour urine collection uncomfortable?
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 17, 2026. · Read our editorial policy