Cushing's disease

Cushing's disease is one cause of Cushing's syndrome, defined by increased secretion of adrenocorticotropic hormone (ACTH) from the anterior pituitary, which is described as secondary hypercortisolism. Most often the cause is a pituitary adenoma, and in some cases it results from excess production of corticotropin releasing hormone by the hypothalamus, which stimulates the adrenal glands to synthesize cortisol. Pituitary adenomas account for about 80 percent of endogenous Cushing's syndrome when syndrome caused by administered corticosteroids is excluded. The condition is distinct from ectopic Cushing syndrome and from the effects of exogenous steroid use, and the equine counterpart is called pituitary pars intermedia dysfunction.