Adrenocorticotropic hormone (ACTH; also adrenocorticotropin, corticotropin) is a polypeptide tropic hormone produced by and secreted by the anterior pituitary gland. It is also used as a medication and diagnostic agent. ACTH is an important component of the hypothalamic-pituitary-adrenal axis and is often produced in response to biological stress (along with its precursor corticotropin-releasing hormone from the hypothalamus). Its principal effects are increased production and release of cortisol and androgens by the cortex and medulla of the adrenal gland, respectively. ACTH is also related to the circadian rhythm in many organisms. Adrenocorticotropin detection can be used in the diagnosis and differential diagnosis of hypopituitary adrenocortical hyperfunction, such as primary aldosteronism, Cushing's syndrome, Cushing's disease, pheochromocytoma, etc.