y-Glutamyltransferase is gamma-glutamyltransferase, and the normal value of gamma-glutamyltransferase is 10-60 U/L for men and 7-45 U/L for women. gamma-glutamyltransferase that is more than 5 times higher than the normal value is serious. γ-Glutamyltransferase is one of the indicators in liver function test, when γ-glutamyltransferase synthesis is hyper or excretion is blocked, serum γ-glutamyltransferase becomes elevated, suggesting that there is an abnormality in the hepatobiliary system. If γ-glutamyltransferase is 5-30 times higher than the normal level, it suggests possible biliary obstruction, such as sclerosing cholangitis and primary biliary cirrhosis. Hepatocellular carcinoma can be more than 10 times the upper limit of the reference value. Prolonged late night, alcohol consumption, fatigue and other factors can also lead to high γ-glutamyltransferase. Therefore, when γ-glutamyltransferase is abnormal, one should go to the hospital in time for further relevant examinations, such as abdominal CT, abdominal ultrasound, pathological biopsy, etc. to make a clear diagnosis.