Bilirubin is a yellow breakdown product of normal heme catabolism. it is responsible for the yellow color of eyes and bruises and the brown color of feces.Its levels are elevated in certain diseases. For example:. Mild rises in bilirubin:. * Hemolysis or increased breakdown of blood.. * Gilbert's syndrome - a genetic disorder of bilirubin metabolism which can result in mild jaundice, found in about 5% of the population.. . Moderate rise in bilirubin:. * Drugs (especially anti-psychotic, some sex hormones, and a wide range of other drugs).. * Hepatitis (levels may be moderate or high).. . Very high levels of bilirubin:. * Neonatal hyperbilirubinaemia, where the newborn's liver is not able to properly conjugate the bilirubin (see jaundice).. * Unusually large bile duct obstruction, eg stone in common bile duct, tumour obstructing common bile duct etc.. * Severe liver failure with cirrhosis.. * Severe hepatitis.. * Crigler-Najjar syndrome. * Dubin-Johnson syndrome