March 1st 2007ABSTRACT: In patients with jaundice and normal liver function, the cause of hyperbilirubinemia is an isolated disorder of bilirubin metabolism. In patients with hyperbilirubinemia who have abnormal liver enzyme levels, hepatocellular disease must be differentiated from cholestatic liver injury. In general, if the cause of jaundice is global hepatocellular dysfunction, the serum alanine aminotransferase and aspartate aminotransferase levels will be predominantly elevated. If the cause is cholestasis, the serum alkaline phosphatase and gγ-glutamyl peptidase levels will be elevated. In most patients, imaging studies will be needed. The initial workup should include abdominal ultrasonography, which can identify dilated intrahepatic and extrahepatic biliary ducts as well as findings that may suggest cirrhosis or signs of portal hypertension, including splenomegaly and ascites.