Corticotropin

Corticotropin is a small amount of peptide hormone secreted by the pituitary gland and is the main regulator of adrenal activity. The secretion of corticotropin is controlled by the adrenocortical hormone-releasing hormone, which is secreted by the hypothalamus in response to the feedback effects of low concentrations of cortisol and stress. Normal corticotropin secretion has the same circadian rhythm as cortisol, high in the morning and low in the afternoon and evening. The determination of corticotropin levels is mainly used for the differential diagnosis of primary and secondary adrenal insufficiency.