Endogenous bilirubin excretion in Bolivian squirrel monkeys with a Gilbert's-like syndrome.

Fasted Bolivian squirrel monkeys (BoSM) exhibit a marked hyperbilirubinemia when compared to fed BoSM. This fasting hyperbilirubinemia (FH) is similar to that in human patients with Gilbert's syndrome. Endogenous bilirubin (BR) excretion (production) into bile was elevated two-fold in BoSM upon fasting. The fraction of injected dose of 3 H-amino-levulinic acid (ALA) incorporated into biliary BR in fasted monkeys was of less magnitude than in fed monkeys and was associated with lower specific activities of 3 H-BR. Both the lower incorporation of ALA and lower specific activities of 3H-BR in fasted BoSM suggest that increased BR excreted may have arisen from pre-existing non-labeled pools of either heme or BR.