TbIL in liver function is also clinically called total bilirubin, and its normal value is generally between 1.7-17.1μmol/L. If the patient’s bilirubin exceeds 17.1μmol/L, it is often considered that the patient has hidden jaundice. If the patient’s bilirubin exceeds 17.1 μmol/L, between 17.1-34.2 μmol/L, then the patient is considered to have hidden jaundice. The so-called hidden jaundice means that although the patient has elevated total bilirubin, the yellowing of the skin and sclera cannot be detected by the naked eye. If the patient’s total bilirubin is further elevated above 34.2 μmol/L, then the yellowing of the skin and sclera can be detected with the naked eye. In such cases, it is necessary to combine direct bilirubin and indirect bilirubin to determine the cause of the elevated bilirubin, whether it is caused by obstruction or hepatocellular necrosis. If direct bilirubin is predominantly elevated, combined with elevated GGT and alkaline phosphatase, it is most likely to be caused by obstructive factors, and further investigations should be performed to clarify the cause of the disease. If indirect bilirubin is predominantly elevated, hepatocellular necrosis is usually considered to be the cause of jaundice.