A red bile pigment found as sodium bilirubinate (soluble), or as an insoluble calcium salt in gallstones, formed fromhemoglobin during normal and abnormal destruction of erythrocytes by the reticuloendothelial system; a bilin withsubstituents on the 2,3,7,8,12,13,17, and 18 carbon atoms and with oxygens on carbons 1 and 19. Excess bilirubin isassociated with jaundice.