Cushing’s syndrome - exogenous

Definition

Exogenous Cushing's syndrome is a form of Cushing's syndrome caused by administration of glucocorticoid (also called corticosteroid) hormones, such as prednisone.

Causes, incidence, and risk factors

Cushing's syndrome is named after the surgeon Harvey Cushing. It is a group of clinical signs and symptoms caused by a chronic excess of glucocorticoids, which are hormones produced by the adrenal glands. Glucocorticoids affect many body functions and are essential for survival, but when the level of these hormones is too high, it can cause serious problems. The most important glucocorticoid is the stress hormone cortisol.

The pituitary gland, a small gland at the base of the brain, regulates cortisol production by secreting a hormone called adrenocorticotropic hormone (ACTH).

Exogenous (caused by something outside the body) Cushing's syndrome is caused by administration of synthetic glucocorticoids, such as prednisone or dexamethasone, for therapeutic purposes (for example, to treat asthma).

Symptoms

• Euphoria, unrelated to life situation
• Moon face (round, red and full)
• Buffalo hump (a collection of fat between the shoulders)
• Central obesity with protruding abdomen and thin extremities
• Weight gain
• Weakness
• Backache
• Headache
• Acne or superficial skin infections
• Purple striations on the skin of the abdomen, thighs, and breasts
• Frequent and easy bruising
• Mental changes
• Impotence or cessation of menses

Additional symptoms that may be associated with this disease:

• Thirst
• Increased urination

Signs and tests

• Current use of cortisone, prednisone or other corticosteroids
• Low or undetectable morning plasma ACTH level
• Low or undetectable morning plasma cortisol level
• Failure to respond to a Cosyntropin stimulation test
• Low free cortisol level if measured in the urine
• High levels of the offending medication in the urine if measured by a special technique called high performance liquid chomatography (HPLC)
• Fasting glucose is sometimes elevated
• Serum potassium may be low
• Low bone mineral density as measure by dual x-ray absortiometry (DEXA)
• High cholesterol, particularly high triglycerides and low high-density lipoprotein (HDL)

Treatment

The suggested treatment is slow withdrawal of corticosteroid therapy under medical supervision. In situations where the medication cannot be discontinued because of the underlying disease (for example, if steroids are needed to treat severe asthma), every effort should be made to reduce the possibility of developing complications.

Excess glucocortoids can raise blood sugar and cholesterol levels, and increase bone loss.

• High blood sugar should be treated aggressively with diet, oral medications, or insulin.
• High cholesterol should be treated with diet or medications.
• Most experts recommend treating patients who will be on steroids for longer than 4-6 weeks in with medication to prevent bone loss (bisphosphonates like alendronate or risedronate). This will reduce the risk of fracture.

Expectations (prognosis)

The effects of adrenal atrophy caused by chronic drug administration should be reversible by withdrawing the drug.

Complications

• Cushing's syndrome symptoms may cause persistent discomfort.
• Steroids may cause diabetes and high cholesterol levels. If left untreated, both of these complications can increase the risk of heart attacks. Untreated high blood sugar over many years can cause damage to the eyes, kidneys and nerves.
• Cushing's syndrome may also lead to weak bones (osteoporosis) and increase the risk of fracture.

Calling your health care provider

Call for an appointment with your health care provider if you are taking a corticosteroid drug and you develop symptoms of Cushing's syndrome.

Prevention

Awareness of the signs and symptoms of Cushing's syndrome may permit early intervention for patients prescribed corticosteroids.

Illustrations

Hypothalamus hormone production

Page Content:

Cushing's syndrome - corticosteroid induced; Corticosteroid-induced Cushing's syndrome; Iatrogenic Cushing's syndrome