Alanine aminotransferase, also known as glutamate aminotransferase, is one of the most common and most important indicators of liver function tests. Usually, high alanine aminotransferase is first considered to be caused by liver disease, but non-disease factors can cause high alanine aminotransferase. For elevated alanine aminotransferase, it is important to pay attention to acute and chronic viral hepatitis, alcoholic liver disease, drug-related hepatitis, fatty liver, hepatocellular carcinoma, hepatic steatosis, and bile duct obstructive disease, and further investigations should be done, such as abdominal ultrasound, CT examination, and other related tests if necessary. If patients are taking antibacterial drugs, lipid-lowering drugs, and other therapeutic drugs, they should also pay attention to the possibility of high alanine aminotransferase caused by drugs. Of course, if high alanine aminotransferase is suspected to be caused by drugs, there should be a history of drug use, which means that patients who have recently been taking certain drugs, especially for a long time, should pay high attention to the effects on the liver. In addition, such as skeletal muscle disease, pulmonary infarction, renal infarction, pancreatic infarction, shock and infectious mononucleosis can also cause mild elevation of transaminases. There are also some easily overlooked causes of high alanine aminotransferase, such as exercise, diet, exertion, alcohol consumption, etc. These non-disease factors are also often misinterpreted as liver disease episodes in elevated aminotransferase, which can lead to overtreatment. Patients who are found to have high alanine aminotransferase should be reviewed regularly for changes in aminotransferase as well as other clinical manifestations to determine what is causing the high alanine aminotransferase and to formulate the most effective treatment based on the results of the tests.