Cushing's Syndrome

Cushing's syndrome

What is Cushing's Syndrome?

Dr Harvey Cushing originally described a tumour of the Pituitary gland, which resulted in over production of cortisol in the adrenal gland. This condition was named Cushing's disease. Subsequently the label Cushing's syndrome was coined to describe any condition that resulted in an excess of cortisol in the body.

There are several different causes of Cushing's syndrome but the symptoms and signs are common to all. In other words the illness pattern presented to the doctor is the same but the underlying disease process is different. It affects approximately two in 10,000 people.

'Cushing's syndrome can involve the pituitary or adrenal glands.'

What causes it?

The most common cause of Cushing's syndrome is the long-term use of high doses of steroids. Synthetic steroids are chemically similar to the cortisol produced by the body and the body responds to high doses of steroids as it would to high doses of cortisol produced in the adrenal glands.

Long term steroid usage is sometimes necessary in the treatment of chronic inflammatory conditions such as chronic forms of arthritis or chronic inflammation of the bowel. Doctors are aware of this possibility and part of the long term monitoring of these conditions is to look out for the development of steroid related side effects.

Cushing's syndrome can also be caused by a tumour in the pituitary gland (Cushing's disease) or the adrenal glands. The pituitary gland is situated in an area of the skull known as the pituitary fossa. This is located in the floor of the skull anteriorly and can be accessed up through the nostrils.

The adrenal glands are two in number and each sits on top of the upper pole of each kidney. Cushing's disease results in overstimulation of the adrenal gland, which in turn produces excessive amounts of cortisol. Tumours of the adrenal glands also cause over production of cortisol. Sometimes the adrenal glands may simply be over active without a tumour being present. This is known as adrenal hyperplasia.

Sometimes alcoholics may develop Cushing's syndrome as a result of advanced liver damage. This process results from their inability to metabolise cortisol normally leading to increased levels of the hormone.

The common denominator in all of the above conditions is that the level of cortisol in the body is high.

What are the symptoms?

There are many different symptoms and signs of Cushing's Syndrome. Some or all of the following may be present:

  • a moon-shaped face.
  • central obesity associated with thin limbs.
  • a pad of fat between the shoulder blades sometimes referred to unflatteringly as a buffalo hump.
  • purple stretch marks across the stomach, skin and breasts. These marks look like the stretch marks associated with pregnancy.
  • reduced muscle mass with a consequent reduction in muscle strength.
  • frequent headaches and back pains.
  • spots on the face, chest and shoulders, some of which may become inflamed and infected.
  • amenorrhoea in women (absence of menstrual periods).
  • impotence in men (inability to get or maintain an erection during sexual intercourse).
  • osteoporosis (brittle bone disease).
  • thirst and an increase in urination - this may be a sign of high levels of sugar in the bloodstream.
  • hypertension (high blood pressure).
  • thinning of the skin and an increase in the levels of hair over the entire surface of the body.
  • growth disturbance in children.
  • depression, which is characterised by mood swings and low levels of motivation. This may prevent patients from seeking medical advice.

How is it diagnosed?

If Cushing's syndrome is suspected, your GP will refer you to an endocrinologist (specialist in glandular disorders) for further investigation. The diagnosis will be confirmed by performing special urine and blood tests, which will show a high level of cortisol in the body. A special test called a Dexamethasone Suppression Test will be carried out and if the cortisone blood level remains high after this test, it is a positive sign of Cushing's syndrome.

How is it treated?

Treatment for Cushing's syndrome depends on the underlying cause of the condition. If it is due to a tumour of the pituitary gland this can be treated very successfully by surgical removal of the tumour. Irradiation of the pituitary gland is sometimes performed as an alternative to surgery.

Tumours of the adrenal glands can also be surgically treated.

Paradoxically the patient may need steroid replacement therapy after surgery because they may no longer be producing sufficient amounts of cortisol in the adrenal glands.

If the syndrome is related to long term usage of steroids the dose of drug can be carefully reduced over time. The symptoms of the syndrome are related to the dose of drug being prescribed so the level of symptoms should reduce as the dose of steroid is tailed off. There are inherent dangers in stopping steroids suddenly so it is most important for the dose reduction to be medically supervised.

What are the long-term prospects?

The various forms of Cushing's syndrome are eminently treatable however the condition usually requires long-term follow up. Some patients may require life long steroid replacement therapy. Cushing's syndrome is potentially fatal if left untreated.

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