What causes Cushing's syndrome?
The most common cause of Cushing's syndrome is taking cortisone-like medicines orally (by mouth) every day for weeks to months. Prednisone is the most common medicine that's taken this way. Inhaled steroid medicines for asthma and steroid skin creams for eczema and other skin conditions don't cause Cushing's syndrome. Even oral medicines taken every day for
short periods of time or every other day for longer periods don't often cause Cushing's syndrome.
The next most common cause of Cushing's syndrome is Cushing's disease. Tumors in the adrenal glands or somewhere else in the body can also cause Cushing's syndrome. The endocrine system consists of glands that produce hormones that regulate processes throughout your body. They include the adrenal glands, pituitary gland, thyroid gland, parathyroid glands, pancreas, ovaries (in females) and testicles (in men).
The adrenal glands produce a number of hormones, including cortisol, which plays a variety of roles in your body. For example, cortisol helps regulate your blood pressure and keeps your cardiovascular system functioning normally. It also helps your body respond to stress, and regulates the way you convert (metabolize) proteins, carbohydrates and fats in your diet into usable energy. However, when the level of cortisol is too high in your body, you may develop Cushing's syndrome.
Cushing's syndrome can develop from a cause that originates outside of your body (exogenous Cushing's syndrome). Taking certain medications over an extended period of time, such as corticosteroid medications by mouth, may cause your cortisol level to rise. That's because these medications are synthetic forms of cortisol. Your doctor may prescribe corticosteroids to treat inflammatory diseases such as rheumatoid arthritis, lupus, asthma and inflammatory bowel disease, or to prevent your body from rejecting a transplanted organ.