Characterization of Cortisol Secretion Rate in Secondary Adrenal Insufficiency.

Context: In secondary adrenal insufficiency (SAI), chronic deficiency of adrenocorticotropin (ACTH) is believed to result in secondary changes in adrenocortical function, causing an altered dose-response relationship between ACTH concentration and cortisol secretion rate (CSR).

Objective: We sought to characterize maximal cortisol secretion rate (CSR) and free cortisol half-life in patients with SAI, compare results with those of age-matched healthy controls, and examine the influence of predictor variables on ACTH-stimulated cortisol concentrations.

Design: CSR was estimated from ACTH (250 μg)stimulated cortisol time-concentration data.