American Board of Internal Medicine (ABIM) Certification Practice Exam

What is the characteristic feature of Gilbert syndrome?

1. Severe conjugated hyperbilirubinemia

2. Mild unconjugated hyperbilirubinemia

3. Complete absence of bilirubin

4. Chronic liver disease

The correct answer is: Mild unconjugated hyperbilirubinemia

Gilbert syndrome is characterized by mild unconjugated hyperbilirubinemia, which results from a genetic mutation leading to reduced activity of the enzyme involved in the conjugation of bilirubin. In this condition, the liver's ability to process bilirubin is affected, but it is typically not severe enough to cause significant health problems. Individuals with Gilbert syndrome often present with slightly elevated levels of unconjugated bilirubin in the blood, which may fluctuate and can be influenced by factors such as fasting, stress, or illness. The mild nature of the hyperbilirubinemia in Gilbert syndrome is what differentiates it from other conditions that result in hyperbilirubinemia. For example, severe conjugated hyperbilirubinemia reflects a more serious liver dysfunction or biliary obstruction, which is not seen in Gilbert syndrome. The absence of bilirubin is not consistent with this syndrome, as it specifically involves elevated levels of unconjugated bilirubin. Finally, Gilbert syndrome does not imply the presence of chronic liver disease; in fact, affected individuals usually have normal liver function tests and overall good health despite their elevated bilirubin levels. This makes the identification of mild unconjugated hyperbilirubinemia a key feature in diagnosing Gilbert syndrome.