High serum alanine aminotransferase is usually indicative of impaired liver function, which can be seen in physiological causes such as heavy drinking and late night, as well as pathologic causes such as viral hepatitis and drug-induced liver injury. High serum alanine aminotransferase is an important indicator in liver function tests, which is mainly distributed in the liver, followed by skeletal muscle, kidney, cardiac muscle and other tissues. Its high value can be seen in physiological and pathological reasons. 1. Physiological causes: such as frequent late nights, fatigue, poor rest, and heavy drinking, etc., can cause liver function abnormalities, resulting in transiently high serum alanine aminotransferase, which can be restored to normal in a few days after removing the triggers. 2. Pathological causes: such as viral hepatitis, drug liver injury, alcoholic liver disease, cirrhosis, autoimmune liver disease, intra- and extra-hepatic cholestasis, etc. can cause high serum alanine aminotransferase. There are many other causes of high serum alanine aminotransferase, which should be emphasized, and timely consultation should be made to identify the cause of the disease and further treatment or therapy as prescribed by the doctor.