Total bilirubin includes direct bilirubin and indirect bilirubin. Direct bilirubin is also called conjugated bilirubin and indirect bilirubin is also called unconjugated bilirubin. The destruction of aging red blood cells in the blood circulation breaks down into indirect bilirubin, which enters the liver with the blood stream and combines with glucuronic acid to produce direct bilirubin. Bilirubin is an indicator of uptake, binding, transport and excretion by hepatocytes. An increase in total bilirubin, dominated by an increase in direct bilirubin, is mainly seen in cholestatic diseases and liver-occupying diseases, such as malignant tumors of the liver, malignant tumors of the bile ducts, malignant tumors of the pancreas, and bilious hepatitis. Elevated total bilirubin, with a predominant increase in indirect bilirubin, is seen in hemolytic diseases, such as hemolytic anemia. Total bilirubin, direct bilirubin, and indirect bilirubin, all three of which are increased, are hepatocellular jaundice. It is mainly caused by inflammation and necrosis of hepatocytes leading to liver dysfunction, such as viral hepatitis, cirrhosis, fatty liver, toxic liver disease, etc.