Bilirubin is an end product of hemoglobin catabolism. It is conjugated with glucuronic acid in the liver, and the conjugated form is cleared from the circulation by excretion in the bile. Both conjugated (direct) and unconjugated (indirect) forms of bilirubin circulate loosely bound to albumin. The assessment of direct bilirubin is helpful in the determination of hepatic disorders. The increase in the total bilirubin associated with obstructive jaundice is primarily due to the direct fraction. Both direct and indirect bilirubin are increased in the serum with hepatitis.