Usually a transaminase of 400 U/L indicates possible impairment of liver function. A decrease in transaminase from 400 U/L to 15 U/L within a few days may be associated with a variety of causes, but the exact duration of a few days is usually not determinable. Causes of elevated aminotransferases include both physiological and pathological factors. Aminotransferases are very sensitive indicators in the body, and even healthy people may have aminotransferase levels that are temporarily outside the normal range. If you have been drinking alcohol or eating unreasonably for a long time, exercising strenuously or overworking before the examination, or taking liver-damaging drugs, etc., it may cause a transient increase of transaminases. After changing unreasonable eating habits, taking sufficient rest, and stopping liver-damaging drugs, the examination transaminases will return to normal levels. However, transaminase can drop from 400U/L to 15U/L in a few days specifically, the time cannot be clarified, and it is mainly related to the etiology of the disease. Clinically, if the aminotransferase is abnormal in two examinations, you must promptly visit the hepatology department of the hospital, and analyze whether there is viral hepatitis or other liver diseases by combining medical history, symptoms, signs and relevant auxiliary examinations, and promptly review and treat. Generally, any elevated transaminases above 100 U/L should be taken seriously.