What causes Acromegaly?

Acromegaly is a disease of the pituitary gland (a small gland found at the base of your brain) that causes too much growth hormone (somatotropin) to be produced. This can occur if there is a disorder of the gland, such as a tumour.

If a pituitary tumour occurs during childhood, it will cause gigantism because of rapid overgrowth of the bones of the arms and legs. If a pituitary tumour occurs after adolescence when the bones have stopped growing, it will cause acromegaly, resulting in enlargement of the head, feet and hands. If childhood gigantism is not treated it will lead to acromegaly in later life.

Acromegaly is a very rare disease. It usually develops in adults between the ages of 30 and 50 years.

What are the symptoms of acromegaly?

Sometimes, the first symptoms of acromegaly are tiredness and sleep disturbance. There is no increase in height in acromegaly, but thickening of the bones causes enlargement of the head, and in particular the lower jaw. In addition, the hands and feet widen and the fingers become much broader. Increased growth of cartilage can increase the size of the nose and ears, while increased cartilage growth in the chest can result in an increased chest girth. Overgrowth of the larynx (voice box) may cause the voice to deepen and the skin may become thicker and coarser in texture. Perspiration may also be a problem, especially in women, and the skin may become oily.

Growth of a pituitary tumour increases pressure within the skull and can cause headaches and visual disturbances. In addition, around a third of people with acromegaly go on to develop diabetes.

The pituitary gland produces other hormones besides growth hormone, including thyroid stimulating hormone (TSH), follicle stimulating hormone (FSH) and adrenocorticotrophic hormone (ACTH). In people with acromegaly the rest of the pituitary gland may become underactive resulting in decreased levels of these hormones. This can cause symptoms such as diminished sexual functions, loss of menstrual periods (amenorrhoea), and symptoms of an underactive thyroid gland. These symptoms may be noticed and a pituitary problem diagnosed before the symptoms of acromegaly are apparent.

What tests are needed?

If your doctor thinks you may have acromegaly you will be referred to a hospital specialist. The specialist will give you a sugary drink and will then monitor the levels of sugar and growth hormone in your blood over the next two to three hours. If your growth hormone levels remain high throughout the test then you have acromegaly. If the test for acromegaly is positive you will need to go for more tests. Your specialist will explain these tests to you.

What treatment is available?

Surgical removal of the pituitary gland may be necessary if it is large and causing increasing hormonal problems. Alternatively, radiotherapy may be used to destroy the part of the pituitary gland that is causing the problem.

In some cases, drug treatment may be prescribed to regulate the release of growth hormone. Drugs used to treat acromegaly include lanreotide (Somatuline® LA and Somatuline® Autogel), octreotide (Sandostatin® and Sandostatin® LAR) and pasireotide (Signifor®). These drugs are given by injection. For short-term treatment, before surgery or radiation therapy, octreotide (as Sandostatin®) needs to be given three times a day. For long-term treatment, injections of lanreotide, octreotide (as Sandostatin® LAR) or pasireotide may be given at intervals of between one and four weeks.

Pegvisomant (Somavert®) is another injectable drug that may be used if other treatments are ineffective or are not tolerated.

Bromocriptine (eg, Parlodel®) is another drug that is sometimes used to treat acromegaly. It suppresses the release of the hormone prolactin and can also reduce levels of growth hormone. It is given in tablet or capsule form.

Further information available from:

The Pituitary Foundation
86 Colston Street
Tel: 0845 450 0376
Helpline: 0845 450 0375 (Monday to Friday, 10am-4pm)

Fact sheet provided by MIMS

Date last reviewed: May 2011

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