The liver is known as the “biochemical factory” of the human body and is responsible for important physiological functions such as metabolism, detoxification and synthesis. Regardless of the cause of liver disease, it will cause abnormal liver function; and these abnormalities can be reflected by testing the relevant indicators of blood. Different tests have different clinical significance, and the following are some of the main liver function indicators: 1. Serum aminotransferases Alanine aminotransferase and aspartate aminotransferase are mainly found in liver cells, and their concentration in liver cells is 1000-5000 times higher than that in blood. If damage occurs to liver cells due to inflammation, these enzymes within the cells are released into the blood, causing an increase in serum aminotransferases. Therefore, serum aminotransferases are the most sensitive indicator of liver cell damage. However, when there is extensive necrosis of liver cells (e.g. fulminant hepatitis) and the intrahepatic aminotransferases have been depleted, the elevation of serum aminotransferases can be insignificant. 2.Bilirubin Under normal circumstances, bilirubin needs to be processed by the liver and then discharged from the body through the bile duct. The bilirubin processed by the liver is called direct bilirubin, and the unprocessed bilirubin is called indirect bilirubin. The sum of direct bilirubin and indirect bilirubin is total bilirubin. Total bilirubin can be elevated in hepatocellular lesions, and indirect bilirubin is predominantly elevated, indicating a decrease in detoxification capacity. However, the liver has a strong ability to compensate for the metabolism of bilirubin, so total bilirubin and indirect bilirubin may not increase in the early stage of the disease. 3. Albumin and globulin Albumin is synthesized by the liver, and its concentration decreases may indicate impaired synthesis function of hepatocytes. However, the half-life of albumin is long, about 15-20 days, so the concentration of albumin can be normal in patients in the acute stage. Decreased albumin levels and increased globulin levels are common in patients with cirrhosis. The normal ratio of albumin to globulin is 1.5-2.5.