The normal range of values for the liver enzyme alanine aminotransferase, or ALT, is about 7 to 56 units per liter of serum, the liquid component of blood, according to MedicineNet. The aspartate aminotransferase, or AST, normal range is about 5 to 40 units per liter of serum.
ALT, concentrated primarily in the liver, is an important indicator of the organ's condition. When the liver is injured, it releases ALT into the bloodstream, explains MedicineNet. AST is present in the liver and other organs, including the heart, kidneys and brain. Since all the organs containing AST release it when they suffer injury, the presence of AST in the bloodstream does not signify liver damage specifically. AST was formerly called serum glutamic oxaloacetic transaminase, or SGOT, and ALT was formerly called serum glutamic pyruvic transaminase, or SGPT, notes WebMD.