AST (Aspartate Aminotransferase)

What it isAST is an enzyme found in liver, heart, skeletal muscle, kidney, and red blood cells. Like ALT, it catalyzes an amino acid metabolism step and leaks into the bloodstream when its host cells are damaged.

DoesReports cell injury — but from any of several tissues, not just liver.

GoodLow AST signals healthy liver and muscle without ongoing damage.

BadElevated AST flags liver disease, muscle injury, cardiac damage, or hemolysis. When AST rises higher than ALT, alcoholic liver disease is the leading suspect.