Bilirubin is the product of the breakdown and destruction of senescent red blood cells in the circulation in the liver, spleen and bone marrow. It includes total serum bilirubin, conjugated bilirubin and unconjugated bilirubin, urinary bilirubin, and urobilinogen. Bilirubin is used clinically to diagnose the presence or absence of hemolysis and to determine the functional status of the liver and biliary system in bile pigment metabolism. 1, elevated serum total bilirubin detection indicates the degree and evolution of jaundice. When it is greater than 17.1 μmol/L, but less than 34.2 μmol/L (normal value for adults is 3.4-17.1 μmol/L), it is occult jaundice or subclinical jaundice. 2. The type of jaundice is judged according to the degree of increase in total bilirubin, conjugated and unconjugated bilirubin. If the total bilirubin is elevated with significantly elevated non-conjugated bilirubin suggests hemolytic jaundice, the total bilirubin is elevated with significantly elevated conjugated bilirubin for obstructive jaundice, and all three are elevated for hepatocellular jaundice. 3.Pre-jaundice of hepatitis, non-jaundiced hepatitis, decompensated cirrhosis, liver cancer, etc., 30%-50% of patients will show elevated bilirubin. 4.Positive urine bilirubin test indicates an increase of conjugated bilirubin in blood, which is commonly seen in, obstructed bile excretion such as cholelithiasis, bile duct tumor, pancreatic head cancer, etc.; hepatocellular damage such as viral hepatitis, acute alcoholic hepatitis, etc.; hepatocellular and obstructive jaundice; bilirubin secretion is also increased in alkalosis.