Cushing’s disease refers to a specific cause of a condition called Cushing syndrome.
Cushing syndrome is due to lengthy exposure to high levels of cortisol. Cortisol is a steroid hormone that is mainly produced by the adrenal glands and released into the bloodstream. It is involved in metabolism, the immune response and the body’s response to stress.
When Cushing syndrome is caused by a pituitary tumor, it is called Cushing’s disease. This particular type of pituitary tumor secretes excessive amounts of ACTH (adrenocorticotropic hormone) which triggers the production and release of cortisol from the adrenal glands.
Cushing syndrome can also be caused by tumors outside the pituitary gland (ectopic ACTH-producing tumors). In addition, adrenal gland tumors and adrenal hyperplasia (increased number of adrenal cells) can cause excessive cortisol levels independent of any triggering by ACTH.
The most common cause of Cushing syndrome is the prolonged use of glucocorticoid (anti-inflammatory “steroid”) medication.
Signs and Symptoms
Some of the more common signs and symptoms of Cushing syndrome include:
- Weight gain, especially in the midsection, with loss of bulk in the arms and legs
- Fatty deposits on the side of the face (moon facies)
- Deposits of fatty tissue in the neck and upper back (buffalo hump)
- Widened, purplish stretch marks (striae) across the stomach, chest, thighs and arms
- Thin, fragile skin that is easily bruised
- New or increased hair growth on the face, chest and abdomen
- Hypertension (high blood pressure)
- Diabetes mellitus (“sugar diabetes”)
- Osteoporosis or osteopenia (loss of bone density)
- Decreased libido (loss of sexual desire or interest)
- Irregular or missed menstrual periods
- Slow healing of abrasions such as cuts, insect bites and infections
The development of symptoms often leads to a physician visit. Diagnosis of a pituitary adenoma starts with a medical history and physical examination, including a vision assessment. The standard tests involved in the assessment of a pituitary adenoma are utilized.
There is one additional test performed specifically in the evaluation of suspected Cushing’s disease/syndrome: petrosal sinus blood sampling. In this neuroradiological procedure, a thin tube is guided into the petrosal sinus on each side of the brain. These sinuses drain the blood away from the pituitary gland. The cortisol level in the blood from each side is then compared to the cortisol level obtained from a vein in the arm. This test is used to determine if the source of excess cortisol is from a tumor in the pituitary gland or elsewhere in the body.
Surgery is the first line of treatment for Cushing’s disease. If needed, cyproheptadine (Periactin®) can suppress the production of ACTH in some tumors. Other medications are available to block the adrenal gland from making cortisol or block cortisol receptors in the body. Surgical removal of both adrenal glands may also be a consideration for persistent severe Cushing’s disease.