ALT is called alanine aminotransferase, AST is called aspartate aminotransferase, ALT and AST are mainly located in the liver cells, ALT and AST are elevated, indicating damage to liver cells, ALT is the most sensitive. A 1-fold increase in serum ALT indicates 1 percent hepatocyte necrosis. Normally, the degree of ALT and AST elevation corresponds to the degree of hepatocyte damage. The distribution of these two enzymes within the hepatocyte is different: ALT is mainly in the hepatocyte plasma, and an elevated ALT reflects damage to the hepatocyte membrane; AST is mainly in the hepatocyte plasma and hepatocyte mitochondria, and its elevation indicates that the hepatocyte is damaged to the organelle level. In acute and mild liver injury, although there is hepatocyte damage, the mitochondria of hepatocytes remain intact and the ALT present in the hepatocyte plasma is mainly released into the blood, and the liver function test result is mainly ALT elevation; the ratio of AST/ALT is <1. In moderate and severe liver injury, the mitochondria of hepatocytes are also damaged, and AST is released from the mitochondria and cytosol, and the test result is AST/ALT ≈1. ≈AST is significantly elevated and AST/ALT is >1 or even >2. This indicates that the hepatocytes and mitochondria are severely damaged and the liver damage is quite severe. Patients taking medication for a long time for chronic diseases should preferably have their liver and kidney functions tested once every 2 to 3 months. If abnormalities are found, promptly adjust the drug variety and dose, and carry out liver and kidney protection treatment to prevent further aggravation of the damage.