AST
Aspartate aminotransferase (AST) is an enzyme found in the liver, heart, skeletal muscle, kidneys, and brain. Unlike ALT, AST is not liver-specific — significant elevations can come from muscle damage (exercise, rhabdomyolysis) or cardiac injury. AST exists in two forms: mitochondrial (mAST) and cytoplasmic (cAST).
Why it matters: The AST/ALT ratio (De Ritis ratio) is often used to explore the likely source of a liver-enzyme change — a higher ratio is commonly associated with alcohol-related liver conditions, a lower ratio with non-alcoholic fatty liver. Raised AST with a normal ALT, especially after exercise, often reflects a muscle source rather than the liver.
May increase with:
May decrease with:
What is AST?
Aspartate aminotransferase (AST) is an enzyme found in the liver, heart, skeletal muscle, kidneys, and brain. Unlike ALT, AST is not liver-specific — significant elevations can come from muscle damage (exercise, rhabdomyolysis) or cardiac injury. AST exists in two forms: mitochondrial (mAST) and cytoplasmic (cAST).
What might a high or low AST mean?
The AST/ALT ratio (De Ritis ratio) is often used to explore the likely source of a liver-enzyme change — a higher ratio is commonly associated with alcohol-related liver conditions, a lower ratio with non-alcoholic fatty liver. Raised AST with a normal ALT, especially after exercise, often reflects a muscle source rather than the liver.
What is the typical reference range for AST?
The general-population reference range shown here is < 34 U/L. Reference ranges describe the general population and are not a personal target — discuss your results with your physician.
What can affect AST?
It may be higher with: Liver disease (hepatitis, cirrhosis), Alcohol consumption (AST rises more than ALT), Intense exercise and muscle damage, Heart attack (myocardial infarction), Medications (statins at high doses), Hemolysis, Rhabdomyolysis, Thyroid disease. It may be lower with: Reduced alcohol intake, Weight loss, Treating underlying liver disease, Rest from intense exercise, Vitamin B6 supplementation (B6 is AST cofactor), Coffee consumption.