VOL: 99, ISSUE: 24, PAGE NO: 32
AETIOLOGY AND RISK FACTORS
AETIOLOGY AND RISK FACTORS
- Hyperthyroidism is a condition characterised by hyperactivity of the thyroid gland. The gland is usually enlarged and secretes greater than normal amounts of thyroid hormones, accelerating the metabolic processes of the body (Mosby, 2002).
- The condition is also known as thyrotoxicosis.
- People aged 30-50 years are most likely to develop the condition and it is more common in women.
- Graves' disease accounts for 75 per cent of cases (McLatchie and Leaper, 2002). The cause of hyperthyroidism is unknown, but it is thought to be a combination of environmental and genetic factors.
- Toxic multinodular goitre accounts for 25 per cent of cases (McLatchie and Leaper, 2002).
- There is often a family history.
- Smoking increases the risk of Graves' disease.
SIGNS AND SYMPTOMS
- Nervousness
- Exophthalmos - often present in Graves' disease, this is an abnormal protrusion of the eyeballs, due to the deposition of excess fat and fibrous tissue behind the eyes. In severe cases the eyelids may not completely cover the eyes during blinking and sleeping, leading to drying of the conjunctiva and predisposing to infection. It does not occur with other forms of thyrotoxicosis.
- Tremor.
- Constant hunger.
- Weight loss.
- Fatigue.
- Heat intolerance.
- Palpitations.
- Diarrhoea or the need to defecate frequently.
- Symptoms usually develop slowly over a number of weeks or months. Because the symptoms can be caused by other problems, diagnosis is not always obvious at first.
COMPLICATIONS
- Untreated hyperthyroidism may lead to death from cardiac failure.
INVESTIGATIONS
- Medical history and physical examination.
- Thyroid function tests.
TREATMENT AND THERAPIES
- Antithyroid drugs such as carbimazole, which reduce the production of thyroid hormones. Carbimazole may take four to eight weeks to take effect and the dose needed will vary from person to person.
- Beta-blockers (propranolol and atenolol, for example) can block some of the effects of a high thyroxine level and are sometimes taken until the above treatments take effect.
- Radioactive iodine: this is given via a capsule or in a drink of water. The overactive thyroid cells absorb the radioactive iodine and as a result the thyroid shrinks, thyroid hormone production falls and blood levels return to normal.
- Surgery: removal of part of the thyroid gland is useful if a large goitre (swelling) is causing problems.
SUPPORT FOR PATIENTS
British Thyroid Foundation, PO Box 97, Clifford, Wetherby, West Yorkshire LS23 6XD. Tel: 0870 770 7933.
WEBSITES British Thyroid Association
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