Hyperthyroidism

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What is Hyperthyroidism?

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Hyperthyroidism is an imbalance of metabolism caused by overproduction of thyroid hormone. The thyroid gland is located in the neck. It produces several hormones which control the way that every cell in the body uses energy (metabolism). The thyroid is part of the endocrine system.

Who gets Hyperthyroidism?

Hyperthyroidism affects 2-5% of all women mainly between 20 and 40 years old. One study estimated the incidence to be 1-2 cases/1000 per year with women affected 10 times more often than men.

Predisposing Factors

Graves' disease - most common cause (due to IgG antibodies binding to the TSH receptor and stimulating thyroid hormone production).

Toxic multinodular goitre: many patients are euthyroid for years before development of thyrotoxicosis. Occurs in older women, drug therapy rarely successful in inducing a prolonged remission

Toxic adenoma

Thyroiditis (De Quervain's Thyroiditis, factitia - surreptitious T4 consumption), drugs (amiodarone), metastatic differentiated thyroid carcinoma and TSH-secretion tumours (e.g. of pituitary).

Thyroid crisis precipitated by infection, stress, surgery or radioactive iodine therapy in an unprepared patient.

Progression

With the exception of Graves' disease and subacute thyroiditis, none of the known causes are associated with spontaneous remission. Thus therapeutic intervention is necessary to alter the natural history of the disease. The severity of complications varies with the duration of the hyperthyroidism and presence of underlying disease. Older patients tolerate hyperthyroidism less well than younger patients, especially the cardiac manifestations.

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