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.

Cushing's disease is caused by a tumor or hyperplasia (excess growth) 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 inflammation (swelling).

• Moon face (round, red, and full)
• Buffalo hump (a collection of fat on the back of the neck)
• Central obesity (person has an abdomen that sticks out and thin arms and legs)
• Weight gain
• Weakness
• Backache
• Headache
• Acne or other skin infections
• Thirst
• Increased urination
• Purple streaks on the skin of the abdomen, thighs, and breasts
• Mental changes
• Impotence
• Stopping of menstruation
• Excessive hair growth in females

Tests are done to confirm there is too much cortisol in the body, then to determine the cause. In general, the fasting glucose may be high, and serum potassium may be low.

These tests confirm too much cortisol:

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

• Serum ACTH levels
• Cranial MRI scan that shows a pituitary tumor
• CRH (corticotropin-releasing hormone) test -- CRH acts on the pituitary gland to bring about the release of ACTH
• Petrosal sinus sampling -- this test measures ACTH levels in the veins that drain the pituitary gland
• Dexamethasone suppression test (high dose)