ALT and AST are mainly found in liver cells, other organs such as kidney, heart muscle, pancreas, muscle, spleen, bile and lung also contain some amount of ALT and AST. ALT is mainly found in the cell plasma and AST is mainly found in the mitochondria of the cell plasma. When cells are damaged (such as hepatitis, myocarditis, pancreatitis, etc.), ALT enters the blood first, and when cells are severely damaged and mitochondria are endangered, AST also enters the blood. In addition, malnutrition, alcoholism, application of certain drugs, fever, etc. can cause a mild increase in transaminases. There are also variations in serum aminotransferases during physiological conditions, such as strenuous activity, physical exercise, and menstruation, when aminotransferases can also be temporarily elevated.