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Medicine > Endocrinology > Hyperthyroidism

Table of contents
1 Definition
2 Signs and symptoms
3 Diagnosis
4 Treatment
5 Prognosis


Hyperthyroidism is the clinical syndrome caused by an excess of circulating free thyroxine and free triiodothyronine, or both. Major causes are Graves' disease (the most common reason with 70-80%), toxic thyroid adenoma, toxic multinodular goitre, and subacute thyroiditis.

Signs and symptoms

Major clinical features are weight loss, fatigue, weakness, hyperactivity, irritability, apathy, depression, polyuria and sweating. Additionally, patients may present with a variety of symptoms such as palpitations, dyspnea, infertility, loss of libido, nausea, vomiting, and diarrhoea.

Neurological manifestations are tremor, chorea, myopathy, and periodic paralysis. Stroke of cardioembolic origin due to coexisting atrial fibrillation may be mentioned as one of the most serious complications of hyperthyroidism.


As to other autoimmune disorders related with thyrotoxicosis, an association between thyroid disease and myasthenia gravis has well been recognised. The thyroid disease, in this condition, is often an autoimmune one and approximately 5% of patients with myasthenia gravis also have hyperthyroidism. Myasthenia gravis rarely improves after thyroid treatment and relation between two entities is yet unknown. Some very rare neurological manifestations that are reported to be dubiously associated with thyrotoxicosis are pseudotumor cerebri, amyotrophic lateral sclerosis and a Guillain-Barré like syndrome.


The major and generally accepted modalities for treatment of hyperthyroidism are :


The prognosis for people that are otherwise in good health is good. Recovery with optimal treatment is often easy to achieve, though this may not always be the case.