Bilirubin is formed by the breakdown of hemoglobin in the red blood cells. The liver is responsible for eliminating bilirubin by first converting it into “conjugated” bilirubin, which is then eliminated in the intestines through the gallbladder and bile ducts (passages that connect the gallbladder to the intestines). The bilirubin found in urine is conjugated bilirubin. This bilirubin has therefore gone into the liver but has been “pushed back” out of the liver before it could reach the intestine through the gallbladder. Increased quantities of bilirubin in the urine can be caused by a number of liver conditions leading to partial or total blockage of the biliary tract (viral hepatitis, toxic hepatitis, bile duct fibrosis, obstruction of the gallbladder by gallstones or obstruction of the bile ducts by a tumour, etc.).