Cushing's Disease

What is Cushing's Disease (pituitary Cushing's syndrome)?

Definition:
Pituitary Cushing's is a condition in which the pituitary gland (an organ of the endocrine system) secretes excess adrenocorticotropic hormone (ACTH).

Causes, incidence, and risk factors:
Cushing's disease is a form of Cushing's syndrome, in which excess cortisol (a stress hormone) is secreted. In the case of Cushing's disease, the problem is caused by a tumor or hyperplasia (excess growth) of the pituitary gland. The pituitary gland is located in the base of the skull and regulates the activities of many glands and body processes.

When ACTH is secreted by the pituitary gland, the adrenal glands release cortisol. In Cushing's disease, there is too much ACTH, which leads to an excess release of cortisol. This hormone, normally released during stressful situations, controls the body's use of carbohydrates, fats, and proteins and also plays a role in suppressing the body's response to inflammation.

Symptoms:

• Moon face (round, red, and full)
• Buffalo hump (a collection of fat on the back of the neck)
• Central obesity with protruding abdomen and thin extremities
• Weight gain
• Weakness
• Backache
• Headache
• Acne or superficial skin infections
• Thirst
• Increased urination
• Purple striations on the skin of the abdomen, thighs, and breasts
• Mental changes
• Impotence or cessation of menses
• Excessive hair growth in females

Signs and tests:
Tests are done to confirm hypercortisolism, then to determine the cause. In general, the fasting glucose may be elevated (glucose intolerance), and serum potassium may be low.

These tests confirm hypercortisolism:

• 24 hour curine cortisol
• 24-hour urine creatinine
• Dexamethasone suppression test (low dose)
• Serial serum cortisol levels that do not show diurnal variation
• Nighttime saliva cortisol levels

These tests determine cause:

• Serum ACTH levels
• Cranial MRI scan that shows a pituitary tumor
• CRH test
• Petrosal sinus sampling
• Dexamethasone suppression test (high dose)

Treatment:
Treatment is by surgical removal of the pituitary tumor, if possible. After surgery, pituitary function may slowly return to normal.

A need for hydrocortisone replacement therapy may become apparent during the recovery process. Irradiation of the pituitary gland may also be used.

If the tumor fails to respond to surgery or radiation, medications to inhibit cortisol synthesis are given.

Support Groups:

Expectations (prognosis):
Untreated, Cushing's disease can cause severe illness, even death. Removal of the tumor may lead to full recovery, but regrowth of the tumor can occur.

Complications:

• High blood pressure
• Diabetes
• Infections
• Compression fractures
• Kidney stones
• Psychosis

Calling your health care provider:
Call your health care provider if you develop symptoms of pituitary Cushing's.

If you have had a pituitary tumor removed, call if signs of complications occur, including signs of recurrence of the tumor.