What is Hyperthyroidism? Features and Treatment of Thyroid Hyperfunction

Because of their widespread effects on body function, excessive production of thyroid hormones gives rise to symptoms in almost all body systems.


The problem affects around 1% of the UK population and women are ten times more likely to suffer from it than men.

Like many endocrine glands the thyroid gland can produce too much hormone or too little. Through its hormones thyroxine and tri-iodothyronine the thyroid plays a major role in body metabolism. It pretty much controls the rate at which energy is used in processes such as utilisation of glucose, fats and proteins and much else. Adequate dietary iodine is a requirement for the manufacture of these hormones.

Both hyperthyroidism – too much hormone and hypothyroidism – too little, are characterised by different but widespread effects on the body.

The thyroid is controlled by the pituitary gland which lies just under the brain. This gland controls all the body’s endocrine glands. The pituitary secretes thyroid stimulating hormone (TSH) which regulates the amount of thyroxine and tri-iodothyronine produced.

Signs and Symptoms of Hyperthyroid Function

Most of the features of hyperthyroidism result from an increase in metabolic rate.

Both hyperthyroidism and hypothyroidism can result in swelling of the thyroid which produces a goitre – a visible swelling in the front of the neck.

  • Heart: palpitation, fast pulse, cardiac failure in the elderly
  • Muscles: weakness and wasting
  • Digestive system: diarrhoea
  • Nervous system: anxiety, tremor
  • Eyes: bulging or staring appearance
  • General: heat intolerance, sweating, weight loss
  • Reproductive system: menstrual disturbance

Causes of Hyperthyroid Function

  • Grave’s disease: the most common reason for hyperthyroidism. Autoimmune in nature, the body produces antibodies which mimic thyroid stimulating hormone.
  • Toxic nodular goitre: much more common in the elderly usually due to long-standing low-level malfunction of the thyroid. Occasionally due to a (normally) benign thyroid tumour. The characteristic bulging eyes of hyperthyroidism are not usually seen in this condition.
  • Thyroiditis: inflammation of the thyroid, probably due to a virus. Also known as De Quervain’s thyroiditis

Treatment of Hyperthyroidism

  • Anti-thyroid drugs: there are several drugs which block the production of thyroid hormones, carbimazole is an example.
  • Surgery: a large part of the thyroid is removed. It’s generally very successful. Occasionally patients will develop an under active thyroid.
  • Radioiodine: this treatment is possible because of the thyroid’s need for iodine to make its hormones. Patients are given a drink containing radioactive iodine which is taken up by the thyroid where the radioactivity sets about destroying the gland’s cells. As with surgery some patients will later develop hypothyroidism.

This article is for information only. If you have any health concerns you should consult your doctor.