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Hyperthyroidism is a condition where the thyroid gland produces too much thyroxine for the body’s needs. It is also known as an overactive thyroid or thyrotoxicosis.

  • Hyper - means “over -“
  • Hypo - means “under -“
  • The terms "hyperthyroid" and "toxic" are interchangeable


  • Graves’ disease - the most common cause
  • A toxic nodular goitre (a goitre is an enlarged thyroid gland)
  • A solitary toxic thyroid adenoma (an adenoma is a clump of cells)
  • Thyroiditis (infection or inflammation of the thyroid gland)

Common Symptoms

A speeding up of mental and physical processes of the whole body, such as

  • weight loss
  • palpitations and a rapid pulse
  • sweating and heat intolerance
  • tiredness and weak muscles
  • nervousness, irritability and shakiness
  • mood swings or aggressive behaviour
  • looseness of the bowels
  • thirst
  • itchiness
  • an enlarged thyroid gland

If the cause is Graves’ disease, you may also have thyroid eye disease. Smokers are eight times more likely to develop thyroid eye disease than non-smokers.


  • By a physical examination and blood tests
  • A low thyroid stimulating hormone (TSH) level with a high thyroxine (T4) level indicate hyperthyroidism

Treatment Options

  • Antithyroid drugs
  • Surgery to remove all or part of the thyroid gland
  • Radioactive iodine to destroy some of the thyroid tissue


Blood tests are carried out

  • every 2 - 6 months when you first start taking anti-thyroid drugs
  • every 6 - 12 months during long-term treatment with anti-thyroid drugs
  • once a year after radioactive iodine or surgery, to check for hypothyroidism

It is well recognised that thyroid problems often run in families and if family members are unwell they should be encouraged to discuss with their own GP whether thyroid testing is warranted.