High liver enzymes are one of the more frequent findings at a routine doctor visit. Potentially indicating liver damage, high liver enzymes are detected by a simple blood test. While liver enzymes are usually found in the liver, damage to this important organ causes the enzymes to leak into the bloodstream. The two liver enzymes that are the most straight-forward to test for and evaluate are aspartate aminotransferase (AST) and alanine aminotransferase (ALT). Normal, or healthy ranges for these liver enzymes are: 1  AST = 5 to 40 units per liter of serum. 2  ALT = 7 to 56 units per liter of serum.