When it comes to liver function, people immediately think of transaminases, and some even think that transaminases are liver function. In fact, there are many types of liver function, and at present, there are more than 700 kinds of tests reflecting liver function, and new tests are still being developed and established, including four main categories: a. Tests reflecting liver cell damage, including serum enzymes and serum iron, etc. Serum enzyme tests are commonly used, such as glutamate aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), cholinesterase ( CHE), gamma-glutamyl transpeptidase (GGT), etc. Clinical studies have shown that among the various enzyme tests, ALT and AST are sensitive indicators of hepatocellular injury and its degree of damage. ALT is the most sensitive to reflect acute hepatocellular injury, and AST is more sensitive to reflect the degree of injury. The normal value of serum ALT activity is 25-40 Rai units. It is generally accepted that the increase is mild when it is less than 2 to 3 times the upper limit of normal; it is significantly higher when it is greater than 5 to 10 times the upper limit of normal; however, the increase is not proportional to the severity of the disease. In acute liver injury (such as acute viral hepatitis or acute attack of chronic hepatitis), ALT is often significantly increased; in the recovery period of acute hepatitis, although ALT is normal, but GGT continues to rise, indicating the chronicity of hepatitis; diseases other than liver, such as heart disease, pneumonia, cholecystitis, pancreatitis, nephritis and other local infections, etc., can cause a mild increase of ALT. Therefore, a mild increase in ALT should be considered as liver disease only when other diseases are excluded. It is important not to put the “hat” of hepatitis on a patient based on only one test of mildly elevated ALT. In addition, ALT can be normal when chronic hepatitis and cirrhosis are progressing insidiously, so a normal ALT does not exclude liver disease. Aspartate aminotransferase, which is second to ALT in sensitivity to hepatocyte damage, can reflect the degree of hepatocyte damage, and if AST is significantly higher than the increase in ALT, it indicates a more serious degree of liver damage. For example, when there are residual lesions during the recovery period of acute hepatitis, or when chronic hepatitis or cirrhosis progresses insidiously, ALT can be normal, but γ-GT remains high; when alcoholic liver injury, cirrhosis When alcoholic liver injury, liver cirrhosis, cancer, γ-GT is also significantly increased. Therefore, the examination of γ-GT in serum can make up for the deficiency of ALT alone, and the two together can not only detect acute liver injury at an early stage, but also track whether chronic liver disease is insidiously progressing or carcinogenic. Tests reflecting liver excretory function To detect the liver’s ability to excrete and clear certain endogenous (bilirubin, bile acids, etc.) or exogenous high uptake substances. If the total bilirubin is greater than 17.1umol/L, it is a case of jaundice. If the bilirubin rises progressively and decreases with ALT, it is called bile enzyme separation, which indicates aggravation of the disease and the possibility of turning into severe hepatitis. Plasma albumin (Alb) and prothrombin time (PT) are routine tests that reflect the storage capacity of the liver by detecting its synthetic function. a decrease in Alb indicates a decrease in protein synthesis, and a prolongation of PT indicates a decrease in the synthesis capacity of various coagulation factors. IV. Tests reflecting interstitial changes in the liver The serum protein electrophoresis test is a common test reflecting interstitial changes in the liver. The degree of increase in γ-globulin can evaluate the evolution and prognosis of chronic liver disease, suggesting that wither cells are hypofunctional and unable to remove endogenous or intestinal antigenic substances from the blood circulation. In addition, serum levels of hyaluronic acid, laminin, type III procollagen peptide and type IV collagen reflect changes in hepatic endothelial cells, lipid storage cells and fibrillogenic cells, which are closely associated with liver fibrosis and cirrhosis.