In Cushing's syndrome, excessive cortisol can be either ACTH-dependent or ACTH-independent. What is an example of an ACTH-dependent source?

In Cushing's syndrome, an ACTH-dependent source of excessive cortisol production typically stems from increased adrenocorticotropic hormone (ACTH) levels. A pituitary adenoma, often referred to as Cushing's disease when it is the cause of Cushing's syndrome, is a benign tumor that secretes ACTH. This overproduction of ACTH stimulates the adrenal glands to produce more cortisol, leading to the symptoms associated with Cushing's syndrome.

The significance of identifying a pituitary adenoma lies in the treatment approach. Surgical removal of the adenoma can often lead to resolution or significant improvement of the symptoms related to Cushing's syndrome. Understanding the source of ACTH is crucial for both diagnosis and management of the condition.

Other possible sources of ACTH that are not the primary focus of this answer include ectopic ACTH syndrome, where ACTH is produced by non-pituitary tumors, and adrenal tumors that produce cortisol independently of ACTH. These sources do not directly involve the pituitary gland's secretion of ACTH in the same manner as a pituitary adenoma.