Which of the following is not a characteristic of Dubin-Johnson syndrome?

• A. Impaired excretion of bilirubin into bile
• B. Hepatic uptake of bilirubin is normal
• C. Inability to conjugate bilirubin
• D. Increased level of bilirubin in urine

Answer: (C)

The situation in Dubin-Johnson syndrome is that the liver can take up bilirubin and conjugate it normally, but the transport of the conjugated bilirubin into the bile canaliculi is defective. This causes conjugated bilirubin to accumulate in the liver and spill into the bloodstream, leading to conjugated (direct) hyperbilirubinemia and bilirubin in the urine. The uptake into liver cells remains intact, and the conjugation process itself is not impaired.

So the statement that is not a characteristic is the inability to conjugate bilirubin, because conjugation is preserved in this condition. The other features—impaired excretion into bile, normal hepatic uptake, and increased bilirubin in urine—fit Dubin-Johnson syndrome.