The liver is the largest substantial organ in the human body and is responsible for a variety of physiological functions; once the “liver” machine “strikes” – that is, “liver failure”, people will definitely not “Human”! In order to find out early whether the liver is working properly or not, there are various laboratory tests available in medicine. Unfortunately, there is no one test that can report the full function of the liver, so tests that reflect different aspects of its function are usually combined to evaluate liver function in a comprehensive manner. Among the more than 700 liver function tests, four types are widely used in clinical practice: 1. Serum enzymology: glutamate aminotransferase (ALT), glutamic oxaloacetic transaminase (AST), alkaline phosphatase (ALP), and gamma-glutamyl transpeptidase (GGT) are most commonly used. ALT is found in the hepatocyte plasma, AST in the mitochondria of hepatocytes, and ALP and GGT mainly in the bile ducts. All diseases that cause hepatocellular injury, whether they target the liver or are systemic diseases, can be characterized by abnormal elevations in serum enzymes, especially ALT/AST. The half-life of ALB is 21 days, and a decrease in ALB may indicate a decrease in the synthetic function of the liver in the last 21 days. The half-life of PA, CHE and prothrombin are short. 3. Liver excretion function: including the ability to excrete and remove endogenous bilirubin, bile acids and exogenous drugs and dyes. Total bilirubin (TBIL) is the sum of direct bilirubin (DBIL) and indirect bilirubin (IBIL), and IBIL is converted into DBIL after binding with specific proteins in hepatocytes; after liver parenchymal cell injury, it can be manifested as hyperbilirubinemia mainly by DBIL elevation; a large number of red blood cell lysis will lead to abnormal bilirubin metabolism mainly by IBIL elevation. 4, liver fibrosis indicators: usually refers to hyaluronic acid, laminin, type III precollagen peptide, and type IV collagen. Stellate cells and fibroblasts in the liver are activated, leading to fibrogenesis in the liver and elevation of the above indicators. Although the above 4 types of tests are commonly used in clinical practice, the functional status of the liver should never be judged on the basis of any one indicator in isolation. The correct diagnosis of the disease must be based on a comprehensive analysis of the medical history, physical examination results and the results of all tests.