Cushing’s disease (also known as Cushing disease, tertiary or secondary hypercortisolism, tertiary or secondary hypercorticism, Itsenko-Cushing disease)^[1][2] is a cause of Cushing’s syndrome characterised by increased secretion of adrenocorticotropic hormone (ACTH) from the anterior pituitary (secondary hypercortisolism). This is most often as a result of a pituitary adenoma (specifically pituitary basophilism) or due to excess production of hypothalamus CRH (Corticotropin releasing hormone) (tertiary hypercortisolism/hypercorticism) that stimulates the synthesis of cortisol by the adrenal glands. Pituitary adenomas are responsible for 80% of endogenous Cushing’s syndrome,^[3] when excluding Cushing’s syndrome from exogenously administered corticosteroids.

This should not be confused with ectopic Cushing syndrome or exogenous steroid use.^[4]