Severe unconjugated hyperbilirubinaemia: one and one makes three?

A 38-year-old housewife presented with a 3-month history of gradually progressive fatigue and deepening jaundice as well as a history of mild fluctuating jaundice since childhood. General examination revealed an obvious icterus. Systemic examination was normal. Laboratory tests confirmed unconjugated hyperbilirubinaemia. Further evaluation yielded a diagnosis of vitamin B12 deficiency on a background of Gilbert's syndrome.