urobilin

Urobilin is a pigment found in bile, which is secreted by the liver. It contributes to the characteristic color of feces. Urobilin is produced in the bone marrow and liver as a byproduct of red blood cell breakdown, specifically from the breakdown of hemoglobin. The amount of urobilin produced is directly related to the rate at which red blood cells are destroyed. While urobilin itself has no known function, it is a product of bilirubin metabolism. Bilirubin, when processed in the intestine, is converted into urobilinogen and then urobilin, some of which is reabsorbed and some excreted in urine and feces.12