print   Print full article

What is it?

Cushing’s syndrome is a group of signs and symptoms caused by the body producing too much cortisol from the adrenal glands. There are two adrenal glands, one on top of each kidney. These glands are triangular in shape. The outer layer of the adrenal glands called the adrenal cortex produces not only cortisol but also aldosterone and the adrenal androgens, mainly dehydroepiandrosterone sulphate (DHEAS). Cushing’s syndrome can also be caused by a patient taking too much of a synthetic glucocorticoid (a steroid like cortisol) for another clinical condition and by other rare causes (see below).

Feedback system for cortisol production



The hypothalamus sends CRH (corticotropin-releasing hormone) to the pituitary, which responds by secreting ACTH. ACTH then causes the adrenals to release cortisol into the bloodstream.

Source: NIDDK Image library

 

Cushing’s syndrome can occur in anyone but more commonly it occurs in adults aged 20-50 years. It is more common in women.

There are several causes of Cushing’s syndrome:

  • Iatrogenic Cushing’s syndrome. When taking synthetic glucocorticoids in high doses and for a long time. These drugs, such as prednisolone and dexamethasone, act like cortisol
  • Cushing’s disease. A pituitary tumour that produces large amounts of adrenocorticotrophic hormone (ACTH)
  • Adrenal tumour. A tumour in the adrenal gland that produces too much cortisol
  • Adrenal nodular hyperplasia. When groups of cells, or nodules, in the adrenal gland produce too much cortisol
  • Ectopic ACTH. A tumour in the body, not associated with the pituitary gland (see cortisol), that produces too much ACTH. This ACTH stimulates the adrenal glands to produce too much cortisol
  • Ectopic CRH. A tumour in the body, not associated with the hypothalamus (see cortisol), that produces too much corticotrophin releasing hormone (CRH). This stimulates the pituitary to secrete large amounts of ACTH that in turn stimulates the adrenal glands to produce too much cortisol
  • In some rare cases Cushing’s syndrome may develop because of gene mutations associated with other clinical conditions. For example a person may have an inherited gene mutation, such as Multiple Endocrine Neoplasia Type 1 or MEN-1, which increases the risk of developing tumours throughout the endocrine system, including pituitary and adrenal tumours.

The first two causes of Cushing’s syndrome are the most common.

There are many symptoms and signs associated with Cushing’s syndrome (see symptoms).


Last Review Date: April 5, 2017