What mechanism causes Cushing's disease?

Cushing's disease specifically refers to a condition caused by excessive production of adrenocorticotropic hormone (ACTH) from the pituitary gland, leading to an overproduction of cortisol by the adrenal glands. This hypersecretion of ACTH is typically due to a pituitary adenoma, which is a benign tumor of the pituitary gland.

In Cushing's disease, the elevated levels of ACTH stimulate the adrenal glands to produce more cortisol, which can lead to all the hallmark symptoms of Cushing's syndrome, such as weight gain, insulin resistance, and skin changes. Recognizing that Cushing's disease is primarily related to pituitary ACTH excess is vital in understanding the condition's pathophysiology and guiding treatment strategies.

Other mechanisms like adrenal adenoma and ectopic ACTH production can lead to Cushing's syndrome but are categorized as different entities within the broader scope of conditions that result in excess cortisol. Treatment with corticosteroids can indeed mimic symptoms of Cushing's syndrome, but it is not the underlying cause of Cushing's disease. Thus, the core mechanism of Cushing's disease is indeed the excess secretion of pituitary ACTH.