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23 November, 2009

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Cushing's syndrome

Cushing’s syndrome is a collection of hormonal disorders characterised by high levels of the hormone cortisol. Another name for Cushing’s syndrome is hypercortisolism. Some people have Cushing’s syndrome symptoms when they take glucocorticoid hormones to treat inflammatory conditions such as asthma, lupus or rheumatoid arthritis. Other causes include tumours of the pituitary and adrenal glands, and tumours in other areas of the body. Around one in 50,000 people are affected by Cushing’s syndrome, with females more susceptible to some forms than males. Without treatment, the disorder can be fatal.

Symptoms
Some of the symptoms include:

Weight gain around the abdomen, and obesity
Wasting of the limbs
A ‘buffalo’ hump of fat high on the back
Round, red and puffy-looking face (‘moon face’)
Thin skin, easily bruised, slow healing and ulcers
Muscular weakness
Thirst
Frequent urination
Headaches
High blood pressure
High white blood cell count, low serum potassium
High blood sugar (in 80 per cent of patients)
Mood swings, irritability, anxiety, depression
Impotence
Irregular menstrual periods or no menstrual periods
Increased facial hair in women
Weakened bones, susceptibility to bone fractures (especially in ribs and spine), osteoporosis and backache
Susceptibility to pneumonia and TB.

The hormone cortisol
Cortisol is made by the adrenal glands. When cortisol levels are too low, the pituitary secretes the stimulating hormone adrenocorticotropin (ACTH). High levels of cortisol prompt the pituitary to decrease ACTH, which slows cortisol production. Cortisol is essential to life. Its functions include:

Helping the body manage stress
Helping to maintain constant blood sugar levels
Inhibiting inflammation
Contributing to the maintenance of constant blood pressure
Contributing to the workings of the immune system.

A range of causes
The symptoms of Cushing’s syndrome are caused by damage to body tissues due to high levels of the hormone cortisol in the blood over a long time. The disorders that trigger high cortisol levels include:

Tumour of the pituitary gland
Tumour of the adrenal gland
ACTH-producing tumours (ectopic) elsewhere in the body
Multiple endocrine neoplasia 1 (MEN1)
Glucocorticoid hormone therapy.

Tumour of the pituitary gland
This form is known as Cushing’s disease and accounts for about seven in 10 cases of Cushing’s syndrome. One type of pituitary gland tumour secretes additional ACTH, which forces the adrenal glands to make too much cortisol. The tumours are usually benign non-cancerous adenomas and they occur more often in women than men (3:1). Complications include diabetes, kidney stones and mental disturbances, such as psychosis.

Tumour of the adrenal gland
This form of Cushing’s syndrome is also known as Cushing’s disease. A tumour on one of the adrenal glands triggers the production of high cortisol levels. The tumours are usually non-cancerous. The pituitary responds by dropping its level of ACTH hormone, which causes the healthy adrenal gland to shrink. Onset of symptoms can be quite rapid, and tends to occur at around 40 years of age.

ACTH-producing tumours
In rare cases, other malignant tumours in the body can produce ACTH. Approximately 17 per cent of Cushing’s disease develops this way. Fifty per cent of cases result from lung tumours. Other causes come from tumours in the thymus, pancreas and thyroid gland. This type of Cushing’s syndrome is sometimes referred to as ‘ectopic’.

Multiple endocrine neoplasia 1 (MEN1)
The pituitary, pancreas, adrenals, thyroid and parathyroid glands belong to the endocrine system. MEN1 is an inherited condition characterised by tumours on at least two of these glands. If the pituitary or adrenals are affected, Cushing’s syndrome can result.

Primary Pigmented Micronodular Adrenal Disease occurs in children and young adults, where there is an increase in the number of cortisol-producing adrenal tumours.

Glucocorticoid hormone therapy
Glucocorticoid drugs are commonly used to ease the symptoms of inflammatory conditions such as asthma, rheumatoid arthritis and lupus erythematosus. These drugs can trigger symptoms of Cushing’s syndrome. However, the effects should reverse once the drug therapy is stopped.

Diagnosis methods
Diagnosis for Cushing’s syndrome involves discovering the high cortisol levels and uncovering the cause. Diagnosis methods may include:

Physical and visual examination, with full family medical history.
Blood tests to check if Cushing’s is of pituitary or ectopic origin and to compare ACTH levels elsewhere in the body. A combination of these two tests gives great accuracy for diagnosis.
Urine tests.
Dexamethasone suppression test using steroids to check the body’s reaction to glucocorticoid drugs.
Magnetic resonance imaging (MRI) scans and computed tomography (CT) scans to check for gland size and evidence of tumours.

Treatment options
Treatment depends on the cause and may include:

Tumour of the pituitary gland - the tumour is surgically removed. Other options include radiation therapy and drug therapy to shrink the tumour and stop it from producing hormones. Hormone therapy for up to two years after surgery may also be required.
Tumour of the adrenal gland - the tumour is surgically removed. Replacement hormone therapy may be necessary in the short term.
ACTH-producing tumours - treatment includes surgery to remove the tumour, followed possibly by chemotherapy, immunotherapy and radiation therapy. Medications can be taken to hamper the ability of the adrenal glands to make cortisol.
MEN 1 - radiation therapy and surgery are used to remove the tumours and associated glands. Ongoing hormone replacement therapy is needed after surgery.
Glucocorticoid hormone therapy - induced Iatrogenic Cushing’s Syndrome - symptoms disappear and the effects reverse once the drugs are stopped. Occasionally a person may need glucocorticoid hormones to successfully manage their inflammatory disorder.

Where to get help

Your doctor
Endocrinologist
The Australian Addison's Disease Association Inc. Tel. (02) 6652 4761; (02) 6657 2571. Website: http://addisons.org.au
The Australian Pituitary Foundation. PO Box 4138 Oatley West, NSW, 2223. Tel. (02) 9594 5550. Email: pituitary@bigpond.com. Website: www.pituitary.asn.au
The Western Australian Cushing's Disease Association Tel. (08) 9402 4394; (08) 9390 2132.

Things to remember

Cushing’s syndrome is a collection of hormonal disorders resulting from high levels of the hormone cortisol.
Causes include certain tumours and glucocorticoid drug therapy for inflammatory disorders.
Without treatment, Cushing’s syndrome can be fatal.

You might also be interested in:
Addison's disease.
Congenital adrenal hyperplasia.
Hormonal (endocrine) system.
Hormones - cortisol.
Hyperglycaemia.
McCune-Albright syndrome.
Pituitary tumour.

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