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 categories are widely used in clinical practice: serum enzymology: glutamate aminotransferase (ALT), 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 in nature, can be characterized by abnormal elevations in serum enzymes, especially ALT/AST, as described above. Liver synthesis/reserve function: serum albumin (ALB), prealbumin (PA), cholinesterase (CHE), and prothrombin time (PT) all reflect liver synthesis and reserve function; ALB has a half-life of 21 days, and a decrease may indicate a decrease in liver synthesis in the last 21 days; PA, CHE, and prothrombin all have short half-lives, and a decrease in PA and CHE and a prolongation of PT may indicate a decrease in liver synthesis in the last few hours. Synthetic function of the liver in the last few hours. Hepatic excretory function: This includes 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). IBIL is converted to DBIL after binding to specific proteins in hepatocytes; after parenchymal cell injury of the liver, it may manifest as hyperbilirubinemia with mainly elevated DBIL; massive erythrocyte lysis will lead to abnormal bilirubin metabolism with mainly elevated IBIL. Indicators of liver fibrosis: usually refers to hyaluronic acid, laminin, type III procollagen 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.