Adrenocorticotropic Hormone (ACTH) is a hormone produced and secreted by the anterior lobe of the pituitary gland. Its primary function is to stimulate the adrenal glands to increase the production of cortisol (the body's primary stress hormone), aldosterone, and androgens. Cortisol plays a critical role in managing the body's response to stress; it also has important functions in metabolism, immune system functions, and blood sugar regulation. Abnormalities in ACTH levels, whether low or high, can lead to various endocrine disorders such as Cushing's syndrome and Addison's disease.