Cushing's disease

Definition

Cushing’s disease is a condition in which the pituitary gland releases too much adrenocorticotropic hormone (ATCH). The pituitary gland is an organ of the endocrine system.

Cushing's disease is a form of Cushing syndrome.

Alternative Names

Pituitary Cushing's disease

Causes, incidence, and risk factors

Cushing's disease is caused by a tumor or excess growth (hyperplasia) of the pituitary gland. This gland is located at the base of the brain.

People with Cushing's disease have too much ACTH. ACTH stimulates the production and release of cortisol, a stress hormone. Too much ACTH means too much cortisol.

Cortisol is normally released during stressful situations. It controls the body's use of carbohydrates, fats, and proteins and also helps reduce the immune system's response to swelling (inflammation).

Symptoms

Symptoms usually include:

• Upper body obesity (above the waist) and thin arms and legs
• Round, red, full face (moon face)
• Slow growth rate in children

Skin changes that are often seen:

• Acne or skin infections
• Purple marks (1/2 inch or more wide) called striae on the skin of the abdomen, thighs, and breasts
• Thin skin with easy bruising

Muscle and bone changes include:

• Backache, which occurs with routine activities
• Bone pain or tenderness
• Collection of fat between the shoulders (buffalo hump)
• Thinning of the bones, which leads to rib and spine fractures
• Weak muscles

Women often have:

• Excess hair growth on the face, neck, chest, abdomen, and thighs
• Menstrual cycle becomes irregular or stops

Men may have:

• Decreased fertility
• Decreased or no desire for sex
• Impotence

Other symptoms that may occur include:

• Mental changes, such as depression, anxiety, or changes in behavior
• Fatigue
• Headache
• High blood pressure
• Increased thirst and urination

Signs and tests

Tests are done to confirm there is too much cortisol in the body, then to determine the cause.

These tests confirm too much cortisol:

• 24-hour urine cortisol
• Dexamethasone suppression test (low dose)

These tests determine cause:

• Blood ACTH level
• Brain MRI
• Corticotropin-releasing hormone test, which acts on the pituitary gland to cause the release of ACTH
• Dexamethasone suppression test (high dose)
• Petrosal sinus sampling - measures ACTH levels in the veins that drain the pituitary gland

Treatment

Treatment involves surgery to remove the pituitary tumor, if possible. After surgery, the pituitary may slowly start to work again and return to normal.

During the recovery process, you may need cortisol replacement treatments. Radiation treatment of the pituitary gland may also be used.

If the tumor does not respond to surgery or radiation, you may get medications to stop your body from making cortisol.

If these treatments are not successful, the adrenal glands may need to be removed to stop the high levels of cortisol from being produced.

Expectations (prognosis)

Untreated, Cushing's disease can cause severe illness, even death. Removal of the tumor may lead to full recovery, but the tumor can grow back.

Complications

• Compression fractures
• Diabetes
• High blood pressure
• Infections
• 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 you have signs of complications, including signs that the tumor has returned.

References

Stewart PM. The adrenal cortex. In: Kronenberg H, Melmed S, Polonsky K, Larsen PR, eds. Williams Textbook of Endocrinology. Philadelphia, Pa: Saunders Elsevier; 2008:chap 14.