Ast
A blood test that measures the level of AST, an enzyme found mainly in the liver and heart, to help assess liver health.
{"Measures AST enzyme levels in your blood","Helps doctors evaluate liver function and detect liver damage","Higher than normal levels may indicate liver injury or disease","Often performed as part of routine liver function tests","Requires a simple blood draw from a vein in your arm"}
Key facts at a glance
- LOINC
- 1920-8
- Short code
- AST
- Synonyms
- —
- Category
- liver
- Sample
- serum
- Container
- Serum Separator Tube (SST) or Plain Red Top Tube
- Units
- U/L
- Ref low
- 8
- Ref high
- 40
- Critical range
- 5 U/L – 1000 U/L
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–120 years
- Method
- enzymatic-colorimetric
- CPT
- 84450
- SNOMED
- 273871001
- Specimen volume
- 3.5 mL to 5 mL
- Stability
- Room temperature (20-25°C): 8 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C): 1 month. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 50
- Lipemia max
- 300
- Icterus max
- 20
- TAT
- 1–4 hours
What is this test?
The AST (aspartate aminotransferase) test is a blood test that measures the amount of this enzyme in your blood. AST is found in various tissues in your body, primarily in the liver, but also in the heart, muscles, kidneys, and brain. When these tissues are damaged, AST is released into the bloodstream, causing elevated levels.
How is the test performed?
A healthcare professional will draw a small sample of blood from a vein in your arm using a needle. The blood sample is then sent to a laboratory for analysis. You do not need to fast before this test, though your doctor may instruct you to do so based on your specific situation.
What do the results mean?
Normal AST levels typically range from 10 to 40 U/L (units per liter). However, the normal range may vary slightly depending on the laboratory. Elevated AST levels may indicate liver damage, hepatitis, cirrhosis, heart attack, muscle injury, or other conditions. Your doctor will interpret your results in combination with other tests and your overall health condition.
Reference range
Reference range: 8-40 U/L. Note: Reference ranges may vary slightly by laboratory due to differences in methodology, instrumentation, and population demographics. Pediatric ranges may differ. Consult laboratory-specific reference intervals.U/L
No fasting required. Avoid strenuous exercise 24 hours prior to collection as it may elevate AST levels. Inform laboratory of current medications including statins, antibiotics, anticonvulsants, and cardiac medications that may affect results.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
AST
Part of panels
Frequently asked questions
Do I need to fast before the AST test?
Are there any risks associated with this test?
What can cause elevated AST levels?
How long does it take to get results?
Sources
- 1Mayo Clinic - AST TestSource
- 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 10, 2026. · Read our editorial policy