What is Cushing's disease primarily caused by?

Cushing's disease is primarily characterized by an overproduction of steroid hormones, particularly cortisol. This excess is often due to an adrenocorticotropic hormone (ACTH)-secreting pituitary adenoma, which stimulates the adrenal glands to produce more cortisol. The elevated levels of cortisol can lead to a variety of symptoms, including weight gain, hypertension, and metabolic disturbances.

The condition is not related to a deficiency in hormone production or adrenal function, which would lead to different disorders like adrenal insufficiency. While there are genetic factors that could contribute to some forms of adrenal disorders, Cushing's disease specifically pertains to an overactivity of the adrenal glands leading to excessive steroid hormone production.