A comprehensive guide to diagnosis and management
Hyperthyroidism is a biochemical diagnosis which occurs when there is pathologically increased thyroid hormone production and secretion by the thyroid gland. Thyrotoxicosis is the clinical manifestation of excess circulating thyroid hormones due to any cause, including hyperthyroidism.
Most common cause of hyperthyroidism in iodine-sufficient areas, accounting for about 80% of cases. It is a systemic autoimmune disorder mediated by thyroid-stimulating hormone (TSH)-receptor antibodies (TRAbs) that stimulate the TSH receptor, leading to thyroid hyperplasia and unregulated excessive production and secretion of thyroid hormone. Peak incidence is at 30–50 years of age, and it is 10 times more common in women than men.
This is the second most common cause of hyperthyroidism in the UK, and is more common in older adults. It occurs in a thyroid gland with at least two autonomously functioning thyroid nodules that secrete excess thyroid hormone. Histologically the nodules are benign follicular adenomas.
This accounts for up to 5% of cases of hyperthyroidism, and is more common in older adults. The nodule produces enough hormone to suppress secretion of TSH from the pituitary, with consequent suppression of the contralateral thyroid lobe.
This is a rare tumour secreting large quantities of TSH, leading to inappropriately normal or elevated TSH levels, with elevated free thyroxine (FT4), and total triiodothyronine (T3) levels. The pituitary does not respond to normal T4 and T3 feedback mechanisms.
This is a rare condition caused by genetic mutations in the thyroid hormone receptor-beta gene. A positive family history supports the diagnosis. Usually the person is euthyroid, but thyrotoxic symptoms may occur.
About 25% of people with Graves' disease have Graves' orbitopathy. Sight-threatening complications include dysthyroid optic neuropathy, severe corneal exposure and ulceration.
A rare and potentially life-threatening complication with mortality rate of about 10%. Features include fever, tachycardia, agitation, hyperthermia, hypertension, atrial fibrillation, heart failure, jaundice, delirium, and coma.
Atrial fibrillation, coronary heart disease, heart failure.
Thyrotoxic periodic paralysis (more prevalent in Asians), reduced bone mineral density and osteoporosis.
Increased risk of pregnancy and fetal complications.
Psychosis can complicate severe cases.