the ratio of serum alanine aminotransferase to serum aspartate aminotransferase; elevated serum levels of both enzymes characterize hepatic disease; when both levels are abnormally elevated and the ALT:AST ratio is greater than 1.0, severe hepatic necrosis or alcoholic hepatic disease is likely; when the ratio is less than 1.0, an acute non-alcoholic hepatic condition is favored.