The total bilirubin test is one of the components of the Liver Health Panel. Bilirubin is an orange-yellow pigment found in bile. As red blood cells normally age and break down, bilirubin—a by-product—is released into the blood and is cleared by the liver. Red blood cells (RBCs) normally degrade after 120 days in the circulation. At this time, a component of the RBCs, hemoglobin (the red-colored pigment of red blood cells that carries oxygen to tissues), breaks down into bilirubin. Approximately 250 to 350 mg of bilirubin is produced daily in a normal, healthy adult, of which 85% is derived from damaged or old red cells that have died, with the remaining amount from the bone marrow or liver. High bilirubin values may indicate a liver function problem, bile duct blockage, or excessive destruction of red blood cells.