Gamma-glutamyltransferase is a kind of enzyme in human body, which mainly exists in liver cells, under normal circumstances the concentration of gamma-glutamyltransferase in serum is low, when the liver cells are damaged, this kind of enzyme will be released from the liver cells in serum, and the abnormally high concentration of this enzyme can be found through the test, which can make a definite diagnosis for all kinds of liver damaging diseases, such as Hepatitis B, Hepatitis C, Hepatitis A, etc. Due to the damage of hepatitis virus to liver cells, γ-glutamyltransferase is released into the serum, and the concentration of the enzyme in the serum will be significantly increased, and at this time, through laboratory tests, it is possible to make a clear judgment on the damage of liver cells. Clinically, in some people, after the application of drugs for liver damage, hepatocellular damage occurs, and the concentration of γ-glutamyltransferase also increases significantly. When hepatoprotective therapy is given, the concentration of gamma-glutamyltransferase decreases significantly.