Bilirubin is the metabolic product of the lysis of aging red blood cells in the body to produce hemoglobin. Bilirubin is divided into direct bilirubin (conjugated bilirubin) and indirect bilirubin (free bilirubin), and the sum of direct and indirect bilirubin is total bilirubin. The increase of bilirubin concentration not only reflects the function of liver cells and the life span of red blood cells, but also has important significance for the differential diagnosis of jaundice. High total bilirubin and indirect bilirubin are mainly due to excessive destruction of red blood cells, which is common in hemolytic anemia, resulting in excessive bilirubin production in the body, exceeding the processing load of the liver, resulting in a significant increase in total bilirubin and indirect bilirubin, and a mild increase in direct bilirubin. In addition, if the total bilirubin and indirect bilirubin are slightly higher than the upper limit of normal value, it may be related to the extrusion and destruction of red blood cells during the blood sampling process, which is of little clinical significance.