What causes presence of bilirubin in urine? what other lab.test to confirm it, ?

Liver / bile duct: Conjugated bilirubin produced by the liver cells is getting released from the cells into the bloodstream rather than the bile ducts, or the bile ducts are sending it back into the bloodstream. Unless this is a lab error, your blood work will also have elevated conjugated bilirubin. This may be a minor problem witih your own metabolism, a medication effect or serious illness.