Pharmacodynamic interpretation of adrenocorticotropin stimulation tests

OBJECTIVE: To report a pharmacodynamic model that describes increases in cortisol concentrations during administration of an adrenocorticotropin (ACTH) infusion, taking into account both steroid secretion and elimination. DATA SOURCES: Previously published data. DATA SYNTHESIS: Using a population estimate of the elimination rate constant for cortisol and equations describing changes in cortisol concentration versus time, a value for the rate of cortisol secretion (R(cort)) was derived. The R(cort) value more directly represents the capacity for adrenal secretion of cortisol. CONCLUSIONS: Pharmacodynamic modeling techniques were used to successfully describe the rate of cortisol secretion during an ACTH infusion. This model can be applied to assess the extent of adrenal suppression after long-term corticosteroid therapy or in the presence of disease states.