Cushing’s Syndrome
Cushing’s syndrome is a group of signs and symptoms caused by abnormally high levels of cortisol. Cortisol is a steroid hormone that helps the body react to physical and emotional stress, regulate blood pressure, and metabolize food. Cortisol is normally secreted in a diurnal pattern, with levels highest in the morning (8 AM) and lowest around midnight. This pattern changes in people who work alternate shifts and sleep at different times during the day. It is frequently disrupted in people who have Cushing’s syndrome.
Cortisol is produced by the cortex, the outer layer of the adrenal glands. The adrenal glands are triangular organs located on the top of each kidney. They are part of the endocrine system, a network of glands that produce hormones that act on organs, tissues, and other glands and that help to regulate systems throughout the body. The adrenal cortex produces the steroid hormones cortisol, aldosterone and the adrenal androgens, primarily dehydroepiandrosterone (DHEA).
Production of cortisol is controlled through a feedback system. When cortisol levels are low, the hypothalamus, a gland located in the lower portion of the brain, produces corticotropin releasing hormone (CRH). This stimulates the pituitary gland, located below it, to produce adrenocorticotropin hormone (ACTH), which then stimulates the adrenal glands to produce and release cortisol. When cortisol levels are high, production of CRH and ACTH are diminished.
Cushing’s syndrome may be caused by a variety of different conditions, including:
- Ingestion of exogenous corticosteroids, such as anti-inflammatory medications prescribed to treat disorders like asthma. Corticosteroid treatment is the most common cause of Cushing’s syndrome.
- A pituitary tumor that produces ACTH; also called Cushing’s disease, this relatively rare condition is the most common cause of excess cortisol production by the adrenal glands (endogenous cortisol).
- Primary overproduction of cortisol by the adrenal gland due to an adrenal tumor or to adrenal hyperplasia.
- A tumor in another part of the body that produces ACTH (ectopic ACTH production).
Cushing’s syndrome can affect anyone, but it is most frequently seen in adults between the ages of 20 to 50 and is more common in women than men. Rarely, a patient may have an inherited gene mutation, such as Multiple Endocrine Neoplasia Type 1 or MEN-1, that increases her risk of developing tumors throughout the endocrine system, including pituitary and adrenal tumors.
Signs and symptoms associated with Cushing’s syndrome vary but frequently include: obesity in the torso with thinner arms and legs, a large rounded face (moon face), increased fat in the neck and shoulder area, and thin fragile skin that bruises easily and heals slowly. Patients may have pinkish streaks that look like stretch marks on their abdomen, thighs, and buttocks, muscle weakness, decreased endurance, osteoporosis, high blood pressure, increased blood sugar, and headaches. Children with Cushing’s syndrome tend to be obese, develop slowly, and may remain short. Women may have excess hair on their face and chest and menstrual irregularities.
