Biomarker · Liver
Aspartate aminotransferase (AST)
AST is an enzyme found in the liver, heart and muscles. Learn what an AST test measures and why it's interpreted alongside ALT.
Written by LON6EVITY Editorial Team · Last updated
Overview
AST is an enzyme present in the liver but also in heart and skeletal muscle.
Why it matters
Because AST is less liver-specific than ALT, it is usually interpreted together with ALT and other liver tests.
Higher results
AST can rise with liver conditions, alcohol use, muscle injury or strenuous exercise. The ratio between AST and ALT can give clinicians additional clues.
How the test is performed
A standard blood sample.
Reference ranges
Reference ranges and targets differ between laboratories, units and guidelines, and depend on age, sex, method and your overall clinical picture. A single result is not a diagnosis — interpret it with a qualified clinician.
Factors that can affect the result
- Strenuous exercise
- Muscle injury
- Alcohol
- Medications
- Liver conditions
Questions people commonly ask
- Why was my AST high after the gym?
- Hard exercise can release AST from muscle. Mention recent training to your clinician.
Related biomarkers
Related tests
Related topics
Understand your biomarkers in context
What does this mean for your own health data? Log your results, follow trends over time and bring an organised summary to your next doctor's appointment.
Sources
- AST Test. MedlinePlus, U.S. National Library of Medicine.
- Liver Function Tests. MedlinePlus, U.S. National Library of Medicine.