Hyperbilirubinemia is a condition in which there is too much bilirubin in the blood. When red blood cells break down, a substance called bilirubin is formed. Babies are not easily able to get rid of the bilirubin and it can build up in the blood and other tissues and fluids of the baby's body. The predominant causes of conjugated hyperbilirubinemia are intrahepatic cholestasis and extrahepatic obstruction of the biliary tract, with the latter preventing bilirubin from moving into the intestines. Viruses, alcohol, and autoimmune disorders are the most common causes of hepatitis. Diagnostic procedures for hyperbilirubinemia may include: Direct and indirect bilirubin levels. A blood test can determine if the bilirubin is bound with other substances by the liver so that it can be excreted (direct), or is circulating in the blood circulation (indirect).