γ-Glutamyl transpeptidase (γ-GT) is widely distributed in human tissues, the most in the kidney, followed by the pancreas and liver, and the most in the liver during embryonic stage, and in the liver mainly in the hepatocyte plasma and intrahepatic bile duct epithelium, γ-GT in normal human serum mainly from the liver. The common reasons for high γ-GT are: 1. In chronic active hepatitis, γ-GT is often 1 to 2 times higher than normal, and if it is elevated for a long time, it may have the tendency of liver necrosis. 2.In acute viral hepatitis, the hepatocytes adjacent to the necrotic area are hyper-synthesizing enzymes, causing the elevation of serum γ glutamyl transpeptidase. 3.The change of serum γ glutamyl transpeptidase in cirrhosis depends on the activity of intrahepatic lesions and their etiology. 4.Alcoholic hepatitis and alcoholic cirrhosis patients almost all have elevated γ glutamyl transpeptidase, which becomes an important feature of alcoholic liver disease. 5, fatty liver patients γ glutamyl transpeptidase is also often elevated, but most of the serum γ glutamyl transpeptidase activity in general nutritional fatty liver does not exceed two times the normal value. 6.In patients with primary or metastatic hepatocellular carcinoma, most of the enzyme is moderately or highly increased, which can be several times or even tens of times greater than normal, while other system tumors are mostly normal. 7.When intrahepatic or extrahepatic bile duct obstruction occurs, the excretion of γ-glutamyl transpeptidase is obstructed, and it flows back to blood with bile, resulting in the rise of serum γ-glutamyl transpeptidase.