Isolated Indirect Hyperbilirubinemia

An adolescent has isolated indirect hyperbilirubinemia. What is the most likely diagnosis?

This is a very common problem. In this setting, the most common cause of isolated indirect hyperbilirubinemia is Gilbert’s syndrome. This is a normal variant that occurs in 5-10% of the population. This is due to low liver activity of bilirubin-uridine glucuronosyltransferase. Thus in Gilbert's syndrome bilirubin is less efficiently excreted into the bile leading to elevated levels of indirect or unconjugated bilirubin in the bloodstream. It generally becomes apparent in adolescence and is more commonly seen in males (2.5-1). Gilbert’s syndrome is not known to cause any symptoms, but the jaundice often becomes apparent with intercurrent illness and fasting.

In this setting, hemolysis should be excluded with a CBC and a reticulocyte count. Occasionally, hypothyroidism can contribute to indirect hyperbilirubinemia.

A probable diagnosis of Gilbert’s can be suggested by:

• Isolated indirect (unconjugated) hyperbilirubinemia on several occasions
• no evidence of hemolysis as indicated by a normal CBC, blood smear, and reticulocyte count
• normal lft’s
• exclusion of other disease processes

Reassurance should be provided so that repeat investigations are not pursued.