Aspartate aminotransferase

Aspartate aminotransferase (AST) is an enzyme found primarily in liver and muscle cells. When cells are damaged, AST leaks into the bloodstream where it can be measured. Elevated AST suggests liver damage from hepatitis, cirrhosis, fatty liver disease, or alcohol use, but can also reflect muscle injury from trauma, intense exercise, or heart attack. AST is typically ordered alongside other liver enzymes (ALT, alkaline phosphatase) to assess liver function. Moderate elevations may be temporary and benign, but persistent elevation requires investigation to identify the underlying cause.