Bilirubin is the main product of the decomposition of old red blood cells . Bilirubin is filtered from the blood by the liver , and excreted in the bile. As the heart becomes increasingly damaged , total bilirubin will increase. The majority of total bilirubin metabolized , and this section referred to as the direct bilirubin . If part of this increase, the cause is usually outside the liver . If the direct bilirubin is low while high total bilirubin , it indicates damage to the liver or in the bile duct in the liver.