At 300 u/l, it is not possible to determine the extent of liver function impairment, and the degree of transaminase elevation is not related to the severity of liver injury. Transaminases are a group of enzymes that catalyze the amino transfer reaction between amino acids and alpha-keto acids, and in liver function tests, they mainly include alanine aminotransferase and aspartate aminotransferase. The former is mainly distributed in the liver and to a lesser extent in tissues such as skeletal muscle, kidney, and cardiac muscle; the latter is mainly distributed in the cardiac muscle, followed by the liver. When the liver is damaged, the permeability of the hepatocyte membrane increases, and the transaminases in the cytoplasm are released into the plasma, causing elevation of plasma transaminases. It can be seen in acute viral hepatitis, chronic viral hepatitis, cirrhosis, cardiac infarction, dermatomyositis and other diseases. Transaminases may be markedly elevated or mildly elevated in different diseases. For example, in acute viral hepatitis, the aminotransferase is usually greater than 300 u/l, but the degree of elevation is not related to the severity of liver injury, and the aminotransferase activity does not rise further during the recovery period of acute hepatitis. When the disease progresses and jaundice deepens, transaminase activity decreases instead, suggesting severe hepatocellular necrosis. When the transaminase is 300u/l, it suggests that the liver function may be damaged, and it is recommended that the patient should seek medical treatment in time, make a clear diagnosis under the guidance of a professional doctor, and assess the severity of the disease, and actively carry out the treatment.