Understanding Your Medical Test: A Complete Guide to What It Is, Why It Is Done, and What Your Results Mean
A blood ammonia test measures the amount of ammonia in your blood, which helps evaluate liver function and detect certain metabolic disorders.
{"Ammonia is a waste product from protein digestion processed by the liver","Elevated levels may indicate liver disease, kidney problems, or metabolic disorders","The test requires a blood sample, typically drawn after fasting","Results help doctors diagnose and monitor conditions like liver failure or hepatic encephalopathy"}
Key facts at a glance
- LOINC
- 1839-0
- Short code
- Ammonia Bld-sCnc
- Synonyms
- Ammonia Bld-sCnc
- Category
- chemistry
- Sample
- whole-blood
- Container
- Lavender-top (EDTA)
- Units
- N/A
- Critical range
- — – 200 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Specimen volume
- 3 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
What is this test? This is a diagnostic test that your healthcare provider orders to gather important information about how your body is functioning and to help identify any medical conditions that may need further evaluation or treatment.
The blood ammonia test measures the concentration of ammonia in your blood. Ammonia is a natural byproduct of protein metabolism in your body. Normally, your liver converts ammonia into urea, which is then excreted by your kidneys. This test helps healthcare providers assess how well your liver and kidneys are functioning.
Why is it performed? Your doctor may recommend this test to confirm or rule out a suspected condition, monitor an ongoing health problem, check how well a treatment is working, or screen for potential issues before they cause noticeable symptoms.
Your doctor may order a blood ammonia test if you have symptoms of liver disease, such as confusion, drowsiness, or unusual behavior. It is also used to monitor patients with known liver or kidney conditions, evaluate unexplained consciousness problems, and assess the effectiveness of treatment for liver diseases.
How to prepare for the test: Follow your provider's specific instructions, which may include fasting for a certain number of hours, avoiding certain foods or medications, and drinking plenty of water. Tell your care team about all medications, supplements, and allergies you have before the day of the test.
You may need to fast (not eat) for 8-12 hours before the test. Avoid smoking before the test as smoking can increase ammonia levels. Inform your doctor about all medications you are taking, as certain drugs can affect test results. The test is usually performed in the morning.
What happens during the test: A trained healthcare professional will carry out the procedure in a comfortable clinical setting, explaining each step as it happens. The test itself is usually quick, and most people are able to return to their normal activities right away, although some tests may require a short recovery period.
A healthcare professional will draw a blood sample from a vein in your arm using a small needle. The sample must be placed on ice and processed quickly, as ammonia levels can change after the blood is drawn. You may feel a brief sting or pinch when the needle is inserted.
Understanding your results: Your results will be compared against standard reference ranges, and your provider will explain what the numbers mean for your specific situation. Values outside the typical range do not always indicate a serious problem, so discuss any questions or concerns with your healthcare team before making decisions about your care.
Normal ammonia levels vary slightly by laboratory but are typically between 15-45 micromoles per liter (μmol/L). Elevated levels may indicate liver disease, liver failure, hepatic encephalopathy, kidney failure, or certain metabolic disorders. Your doctor will interpret your results based on your overall health and other test findings.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
The blood ammonia test is primarily used to assess liver function and detect liver disorders. Elevated ammonia levels are commonly seen in patients with liver cirrhosis, acute liver failure, and hepatic encephalopathy (a condition where brain function is impaired due to liver disease). The test is also valuable in monitoring patients with portal hypertension, Reye's syndrome, and certain inherited metabolic disorders. Additionally, it helps evaluate kidney function, as the kidneys play a role in ammonia excretion.
Frequently asked questions
Is the blood ammonia test painful?
What can cause false high ammonia levels?
What happens if my ammonia levels are high?
How often do I need this test?
Are there any risks with this test?
Sources
- 1
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- 3
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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