ACTH

Adrenocorticotropic hormone, also called corticotropin or ACTH, is a polypeptide hormone produced and secreted by the anterior pituitary gland. It is a core part of the hypothalamic-pituitary-adrenal axis, released during physical and psychological stress alongside corticotropin-releasing hormone from the hypothalamus. Its principal effect is to stimulate the adrenal cortex to increase production and release of cortisol and androgens. ACTH is a 39 amino acid peptide with a molecular weight of about 4540 daltons and a blood half-life of ten to thirty minutes, formed by cleavage of the larger precursor protein proopiomelanocortin. It acts by binding to ACTH receptors, seven-membrane-spanning G protein-coupled receptors found mainly on cells of the adrenal cortex. Beyond its role as a natural hormone, synthetic ACTH is used clinically both as a diagnostic agent to test adrenal gland function and as a treatment for certain conditions including infantile spasms. Low ACTH is associated with secondary and tertiary adrenal insufficiency, while persistently high ACTH marks primary adrenal insufficiency, and pituitary tumors that oversecrete ACTH cause Cushing's disease through the resulting excess cortisol.