Cortisol is a steroid hormone that is released from the adrenal glands that sit atop the kidneys. Its main functions are to control glucose and insulin, to aid in metabolic processes and to suppress the immune system. Cortisol also plays an important role in the body's stress management and even fertility in women. Consistently high cortisol levels can lead to Cushing's syndrome, a rare hormonal disorder that causes upper body obesity, fatigue, muscle weakness, high blood pressure, high blood glucose and depression. Elevated cortisol levels can be caused by both internal and external factors.
Cushing's Disease
Cushing's disease refers to a syndrome in which the patient has a single benign pituitary gland tumor that secretes excess adrenocorticotropin (ACTH), a hormone that stimulates the adrenal glands to produce cortisol. Extra ACTH increases the amount of cortisol in circulating blood. The National Institutes of Health reports that Cushing's disease affects women five times more often than men.
Adrenal Gland Tumors
Both benign adrenal gland tumors, or adenoma, and malignant tumors, or adrenal cell carcinoma, can cause the adrenal glands to secrete more cortisol. In some cases, the tumor is considered "functional." This means that in addition to causing increased cortisol to be released from the adrenal glands, the tumor cells produce extra cortisol as well.
ACTH-Producing Tumors
Excessive cortisol also can be caused by ACTH-secreting tumors located in areas of the body outside of the pituitary gland, also known as ectopic ACTH. According to the National Institutes of Health, ectopic ACTH-secreting tumors are more common in men than in women and can be benign or malignant. The Cushing's Support and Research Foundation reports that the most common ACTH-producing tumors are found in the chest in up to 52 percent of patients. Etopic ACTH also can be produced by other tumors such as thymomas in 5 percent of patients, pancreatic islet tumors in 1 percent of patients and medullary carcinomas of thyroid in 2 percent of patients.
Stress
During the body's normal stress response, the pituitary gland increases its release of ACTH, which, in turn, increases cortisol levels. The increased cortisol provides additional energy, increased immunity and a lowered pain threshold and helps to maintain the body's homeostasis. Ideally, when the stressful episode is over, the body's relaxation response is activated and cortisol production decreases. However, if the body's stress response is continuously activated, a state of chronic stress occurs, resulting in prolonged elevated cortisol levels.
Drugs
Another cause of elevated cortisol levels is use of certain medications, most commonly glucocorticoids and estrogen compounds. Glucocorticoids are steroid compounds that simulate the physiologic effects of cortisol. They are used mainly for anti-inflammatory and immunosuppressive purposes. The majority of cases of Cushing's syndrome are due to long-term administration of high amounts of glucocorticoids.
Less frequently, elevated cortisol levels and Cushing's syndrome have been linked to extended use of high-dose medroxyprogesterone, an estrogen compound with glucocorticoid activity. Typically, the lower doses used for hormonal replacement therapy and for contraception are not associated with Cushing's syndrome.
