Cushing's syndrome is a disease caused by an excess of cortisol production or by excessive use of cortisol or other similar steroid (glucocorticoid) hormones. Cortisol excess produces significant and serious change in the appearance and health of affected individuals. Some people may have more dramatic changes, some might look more masculinized, some may have more blood pressure or weight changes. Symptoms usually include fatigue, weakness, depression, mood swings, increased thirst and urination, and lack of menstrual periods in women. If untreated, Cushing's syndrome will cause continued weakness of the muscles, fatigue, poor skin healing, weakening of the bones of the spine (osteoporosis) and increased susceptibility to some infections including pneumonia and tuberculosis.
Spontaneous Cushing's syndrome is relatively rare and most commonly affects adults aged 20 to 50. It has a greater frequency in women than men. An estimated 5 to 25 of every million people are affected each year. Ectopic ACTH as a cause of Cushing's Syndrome is more common because of the high rate of lung cancer (about 660 per million per year), but it often goes unrecognized. The incidence increases with age. Adrenal tumours are relatively rare, and cause Cushing's Syndrome in only 2 people per million per year for both adenomas and carcinomas. Both are also 4 to 5 times more common in women than men. Iatrogenic Cushing's Syndrome from taking steroid medication is extremely common because of the widespread use of glucocorticoid hormones for asthma, rheumatoid arthritis, systemic lupus inflammatory bowel disease, some allergies and other inflammatory diseases.