Jaundice in an adult patient can be caused by a wide variety of benign or 
life-threatening disorders. Organizing the differential diagnosis by prehepatic, 
intrahepatic, and posthepatic causes may help make the work-up more manageable. 
Prehepatic causes of jaundice include hemolysis and hematoma resorption, which 
lead to elevated levels of unconjugated (indirect) bilirubin. Intrahepatic 
disorders can lead to unconjugated or conjugated hyperbilirubinemia. The 
conjugated (direct) bilirubin level is often elevated by alcohol, infectious 
hepatitis, drug reactions, and autoimmune disorders. Posthepatic disorders also 
can cause conjugated hyperbilirubinemia. Gallstone formation is the most common 
and benign posthepatic process that causes jaundice; however, the differential 
diagnosis also includes serious conditions such as biliary tract infection, 
pancreatitis, and malignancies. The laboratory work-up should begin with a urine 
test for bilirubin, which indicates that conjugated hyperbilirubinemia is 
present. If the complete blood count and initial tests for liver function and 
infectious hepatitis are unrevealing, the work-up typically proceeds to 
abdominal imaging by ultrasonography or computed tomographic scanning. In a few 
instances, more invasive procedures such as cholangiography or liver biopsy may 
be needed to arrive at a diagnosis.