What Is Cushing's Disease?
Cushing's disease is a hormonal disorder caused by a benign (non-cancerous)
pituitary tumor which produces large amounts of ACTH (adrenocorticotropin). This excess ACTH causes the body to produce extra cortisol, resulting in Cushing's disease.
Cushing's disease affects women five times more frequently than men.
Understanding Cortisol and the Pituitary Gland
Normally, the production of cortisol follows a precise chain of events. First, the hypothalamus, a part of the brain that is about the size of a small sugar cube, sends corticotropin-releasing hormone (CRH) to the pituitary gland. CRH causes the pituitary gland to secrete ACTH, a hormone that stimulates the adrenal glands. When the adrenals, which are located just above the kidneys, receive the ACTH, they respond by releasing cortisol into the bloodstream.
Cortisol performs vital tasks in the body. Cortisol helps:
- Maintain blood pressure and cardiovascular function
- Reduce the immune system's inflammatory response
- Balance the effects of insulin in breaking down sugar for energy
- Regulate the metabolism of proteins, carbohydrates, and fats
- Assist the body as it responds to stress.
When the amount of cortisol in the blood is adequate, the hypothalamus and pituitary release less CRH and ACTH. This ensures that the amount of cortisol released by the adrenal glands is precisely balanced to meet the body's daily needs. However, if something goes wrong with the adrenals (or with their regulating switches in the pituitary gland or the hypothalamus) the level of cortisol produced may be more or less than what the body needs.
The pituitary gland sits in the middle of the head in a bony box called the sella turcica. The eye nerves sit directly above the pituitary gland. Enlargement of the pituitary gland can cause localized symptoms, such as
headaches or visual disturbances.
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