Clinical: Clinical Review.(Disease/Disorder overview)

Hyperthyroidism

Contributed by Dr Sudesna Chatterjee, consultant physician and specialist in diabetes and endocrinology, Stoke Mandeville Hospital, Buckinghamshire

Section 1: Epidemiology and aetiology

Hyperthyroidism is one of the most common endocrine conditions worldwide.

It occurs in 1-2 per cent of the population with greater incidence in iodine-deficient regions and is 10 times more common in women than men between the ages of 20 and 40 years. In the UK Whickham survey, the prevalence of hyperthyroidism was estimated at 0.8 per 1,000 per year in women and less than 0.1 per 1,000 per year in men.1

Aetiology

Hyperthyroidism, or thyrotoxicosis, is defined by excess circulating thyroid hormones. It is caused mainly by stimulation of thyroid tissue by thyroid-stimulating hormone (TSH) receptor stimulating antibodies (TRAb) as in Graves' disease, or by autonomous production by groups of benign cells, for example with multinodular goitre or toxic adenoma.

Very rarely, secondary hyperthyroidism is due to TSH overproduction by a benign tumour in the anterior pituitary gland.

Graves' disease is the most common cause of thyrotoxicosis in young people, whereas multinodular goitre accounts for 50 per cent of cases in patients over 60 years.

Rarer causes include drugs such as amiodarone, lithium or thyroxine, solitary adenoma or thyroiditis, especially in the postpartum period.

Hyperthyroidism associated with amiodarone therapy is more prevalent in iodine-deficient areas and in patients with underlying thyroid disease.

Risk factors

Around 60 per cent of patients with hyperthyroidism have a family history of autoimmune thyroid disease and …