Cushing syndrome

Author: Vanessa Ngan, staff writer, 2005.

What is Cushing syndrome?

Cushing syndrome is a hormonal disorder caused by prolonged exposure to inappropriately high levels of plasma glucocorticoid (also referred to as cortisol) hormones. Glucocorticoid hormones maintain glucose regulation, suppress the immune response and are released as part of the body's response to stress. The production of cortisol from within the cortex of the adrenal glands is regulated by a small gland just below the brain called the pituitary gland.

There are several causes of Cushing syndrome:

Who is at risk of Cushing syndrome?

The most common cause of Cushing syndrome is from the use of exogenous glucocorticoids for periods of several months or longer.

Cushing syndrome caused by an adrenal or pituitary tumour affects women five times more frequently than men and most commonly occurs between 25-40 years of age.

What are the signs and symptoms of Cushing syndrome?

The most distinctive features of Cushing syndrome are the deposits of fat over the clavicles and back of the neck (buffalo hump), the rounded puffy face (moon face, tomato face) with the contrasting slender wasted limbs. Bones are weakened, and activities such as bending, lifting or rising from a chair may lead to backaches, rib and spinal fractures. Many people suffer severe fatigue, weak muscles, high blood pressure, high blood sugar, irritability, anxiety and depression.

Signs and symptoms appearing in the skin include:

How is the diagnosis made?

Although the diagnosis of Cushing syndrome may be made clinically, it is important to confirm it and explain the reasons for it. Laboratory tests may include:

Imaging to locate a tumour may include CT scan, MRI or ultrasound.

What is the treatment for Cushing syndrome?

Treatment depends on the cause of the glucocorticoid excess and may include surgery, radiation, chemotherapy or drug therapy.

Exogenous steroid administration
  • Reduce the dose of corticosteroid drug to lowest dose adequate for control of the original disease
  • Once control established, consider increasing the dose of corticosteroids and giving on alternate days to lessen side effects.
Pituitary tumours
  • Most commonly treated by surgical removal of the tumour, known as transsphenoidal hypophysectomy
  • Where surgery has failed or as an alternative to surgery, radiation therapy to the pituitary gland over a 6 week period
Adrenal tumours
  • Surgery is the mainstay of treatment for benign as well as cancerous tumours of the adrenal glands. Prognosis is poor for cancerous tumours.
Ectopic ACTH syndrome
  • Removal of cancerous tissue that is secreting ACTH through surgery, radiotherapy, chemotherapy, immunotherapy, or a combination of these treatments.

Drugs that inhibit glucocorticoid hormones (e.g. mitotane) may sometimes be used in conjunction with the above therapies.

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