AST (Aspartate Aminotransferase)
AST (aspartate aminotransferase, formerly SGOT) is an enzyme found in the liver, heart, skeletal muscle, kidneys, and red blood cells. Because it is less liver-specific than ALT, AST is interpreted alongside ALT and other liver tests rather than alone.
Normal Range
Men: 8–48 U/L; Women: 8–43 U/L
Reference ranges may vary slightly between laboratories. Always interpret your result in context with your doctor.
Why is AST measured?
AST is part of the standard liver panel and helps distinguish causes of liver injury when interpreted alongside ALT. The AST/ALT ratio is a useful diagnostic clue. AST is also useful for monitoring muscle disorders and certain heart conditions.
High AST means…
Elevated AST suggests damage to one of the tissues containing it — most commonly the liver, but also heart, muscle, or red blood cells. The pattern matters: AST higher than ALT (ratio > 2) suggests alcoholic liver disease; isolated AST elevation may indicate muscle injury.
Low AST means…
Low AST is uncommon and rarely clinically significant. It may occasionally indicate vitamin B6 deficiency.
Symptoms associated with abnormal AST
When AST is high:
- Often no liver-specific symptoms
- Fatigue
- Right upper abdominal pain (liver cause)
- Muscle pain or weakness (muscle cause)
- Chest pain (cardiac cause)
- Jaundice in advanced disease
When AST is low:
- Usually asymptomatic
How to improve your AST
- If AST and ALT are both raised, the same liver-supportive measures apply: limit alcohol, lose excess weight, avoid unnecessary medications.
- If AST is elevated in isolation, ask whether it could be muscle-related (recent intense exercise, statin use, or muscle disorder).
- Coffee consumption is associated with lower AST and reduced cirrhosis risk.
- Always interpret AST alongside ALT — the ratio is more informative than either value alone.
Frequently asked questions about AST
What does an AST/ALT ratio above 2 mean?
An AST/ALT ratio greater than 2:1 strongly suggests alcoholic liver disease. The ratio falls below 1 in most other liver disorders, including non-alcoholic fatty liver disease and viral hepatitis.
Can exercise raise AST?
Yes — strenuous exercise, particularly weight training or long-distance running, can raise AST significantly because it is also found in muscle. Mild post-exercise elevations resolve within 24–48 hours.
Medical Sources
This page is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider about your individual results.