Corticosteroid production in abetalipoproteinemia: evidence for an impaired response to ACTH

The concept that an inherent absence of plasma LDLs may be associated with a reduced synthesis of steroid hormones has been evaluated in two patients with ABL. Basal production of adrenal corticosteroids, assessed by the concentrations of serum cortisol and the rates of excretion of urinary 17OHCS and 17KS and urine free cortisol, was normal in both patients with ABL. Prolonged stimulation (24 to 36 hr) with ACTH, however, disclosed an impairment in adrenal corticosteroid production in both patients with ABL (as compared to normolipidemic controls), which was manifest by lower serum cortisol levels, reduced rates of urinary excretion of 17OHCS and 17KS and a marked decrease in the excretion of urine free cortisol. These results provide in vivo evidence to support the view that plasma LDLs serve as an important source of cholesterol for adrenal corticosteroid synthesis during prolonged stimulation with ACTH but show that a total absence of LDL does not impair adrenal steroidogenesis in the basal state.