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hyperthyroidism
hyperthyroidism The classic picture of excessive thyroid activity is that of a patient with Graves' disease — a form of thyrotoxicosis. Robert Graves was a renowned Dublin physician, whose bicentenary was celebrated in 1996. In addition to promoting a radical innovation in medical education — ward rounds with bedside teaching — he wrote in 1835 the first clear description of this disease. In a short paper titled ‘Palpitation of the heart with enlargement of the thyroid gland’, he recognized the defining significance of a ‘triad’ of symptoms: goitre, protruding eyes, and palpitations.
In the UK about 2% of women will suffer from thyroid overactivity (hyperthyroidism). It is ten times less likely among men. The hyperthyroidism of at least 50% of the patients is due to Graves' disease — now known to be an autoimmune condition. Normally, thyroid activity is subject to positive regulation by thyroid stimulating hormone (TSH), which is secreted from the pituitary and stimulates thyroid growth and function. Very rarely, thyrotoxicosis is caused by excessive production of TSH. Hyperthyroidism of non-autoimmune origin is usually due to either a toxic nodular goitre (‘Plummer's disease’, after a physician at the Mayo Clinic in the 1920s) or a toxic adenoma — a benign tumour in which the cells retain the follicular arrangement characteristic of the thyroid gland. In complete contrast, the overactivity encountered in Graves' disease is due to the aberrant production of autoantibodies, known as thyroid stimulating antibodies. These mimic TSH and persistently stimulate the thyroid follicular cells. These antibodies are unique in having a stimulating as opposed to a blocking action. They were first described in a classic series of studies conducted in the 1950–60s by Adams and Purves in the University of Otago. Thyroid overactivity results in the secretion of excessive amounts of thyroid hormones into the bloodstream. As a consequence, the clinical symptoms are the exaggerated effects of thyroid hormones on peripheral tissues. The basal metabolic rate increases and the effects of some other hormones — notably adrenaline — are potentiated. The symptoms include persistent weight loss despite a healthy appetite, sweating, hand tremor, and often a goitre. The patient is agitated, fatigues easily, and is intolerant of heat. Adrenaline potentiation is most seriously manifested by atrial fibrillation (a fast, irregular heartbeat). Some symptoms are additionally indicative of an autoimmune origin of the hyperthyroidism — Graves' disease. These include eye signs, which range from protruding eyes (exophthalmos) to — in very rare cases — optic nerve compression with loss of vision. There can also be a characteristic thickening of the skin over the lower legs and on the tops of the feet or big toes. If there is a goitre, it is a diffuse enlargement and an isotope scan shows that the entire gland is uniformly overactive. A hyperthyroid patient may be rendered euthyroid (hormone levels within normal limits) with antithyroid drugs, for example carbimazole, which inhibit the biosynthesis of thyroid hormones. After treatment for 12–18 months, spontaneous remissions occur in about half the patients with Graves' disease, so that if the antithyroid drugs are withdrawn the symptoms do not recur. This is typical of the ‘waxing and waning’ of some autoimmune conditions, and remissions were described without specific treatment in the early nineteenth-century reports. By contrast, spontaneous remission will not occur in patients suffering from hyperthyroidism of non-autoimmune origin. If remission is not achieved, long-term treatment usually requires partial or total elimination of the thyroid. This is achieved either by the use of radioiodine or by surgical removal (thyroidectomy). N. J. Marshall See also goitre; hormones; hypothyroidism; thyroid. |
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COLIN BLAKEMORE and SHELIA JENNETT. "hyperthyroidism." The Oxford Companion to the Body. 2001. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. COLIN BLAKEMORE and SHELIA JENNETT. "hyperthyroidism." The Oxford Companion to the Body. 2001. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O128-hyperthyroidism.html COLIN BLAKEMORE and SHELIA JENNETT. "hyperthyroidism." The Oxford Companion to the Body. 2001. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O128-hyperthyroidism.html |
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Hyperthyroidism
HYPERTHYROIDISMHyperthyroidism is the condition that reflects excessive concentrations of thyroid hormones, due to any cause. The resulting hypermetabolic state causes increased heat production and accelerates many of the bodies' processes. Common causes are Graves' disease, hyperfunctioning benign thyroid tumors, and thyroid inflammations. Untreated, patients may have severe and progressive disability that includes weight loss, muscle weakness, loss of mineral from their bones, and increased risk for dangerous heart arrhythmias. Available treatments include one of several "antithyroid drugs," such as methimazole and propylthiouracil, that prevent overproduction of thyroid hormones, and radioctive iodine (I-131) treatment or surgery, which either destroy or remove the thyroid tissue. Martin I. Surks (see also: Goiter; Hypothyroidism; Thyroid Disorders; Thyroid Function Tests ) BibliographyWartofsky, L. (1999). "Hyperthyroidism." In Atlas of Clinical Endocrinology, Vol. 1: Thyroid Diseases, ed.M. I. Surks. Philadelphia, PA: Current Medicine. |
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Surks, Martin I.. "Hyperthyroidism." Encyclopedia of Public Health. 2002. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. Surks, Martin I.. "Hyperthyroidism." Encyclopedia of Public Health. 2002. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1G2-3404000443.html Surks, Martin I.. "Hyperthyroidism." Encyclopedia of Public Health. 2002. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3404000443.html |
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hyperthyroidism
hy·per·thy·roid·ism / ˌhīpərˈ[unvoicedth]īroiˌdizəm/ • n. Med. overactivity of the thyroid gland, resulting in a rapid heartbeat and an increased rate of metabolism. Also called thyrotoxicosis. DERIVATIVES: hy·per·thy·roid adj. hy·per·thy·roid·ic / -[unvoicedth]īˈroidik/ adj. |
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"hyperthyroidism." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "hyperthyroidism." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O999-hyperthyroidism.html "hyperthyroidism." The Oxford Pocket Dictionary of Current English. 2009. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O999-hyperthyroidism.html |
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hyperthyroidism
hyperthyroidism (hy-per-th'y-roid-izm) n. overactivity of the thyroid gland, either due to a tumour, overgrowth of the gland, or Graves' disease. apathetic h. a condition seen in patients with thyrotoxicosis, characterized by slow atrial fibrillation and depressive illness. See thyrotoxicosis.
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"hyperthyroidism." A Dictionary of Nursing. 2008. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "hyperthyroidism." A Dictionary of Nursing. 2008. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O62-hyperthyroidism.html "hyperthyroidism." A Dictionary of Nursing. 2008. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O62-hyperthyroidism.html |
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hyperthyroidism
hyperthyroidism Excessive production of thyroid hormone, with enlargement of the thyroid gland. Symptoms include protrusion of the eyeballs, rapid heart rate, high blood pressure, accelerated metabolism, and weight loss. See also hypothyroidism
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"hyperthyroidism." World Encyclopedia. 2005. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "hyperthyroidism." World Encyclopedia. 2005. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O142-hyperthyroidism.html "hyperthyroidism." World Encyclopedia. 2005. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O142-hyperthyroidism.html |
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hyperthyroidism
hyperthyroidism Overactivity of the thyroid gland. This condition causes an increase in basal metabolic rate, with such symptoms as rapid pulse and weight loss. It is sometimes associated with a goitre. Compare hypothyroidism.
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"hyperthyroidism." A Dictionary of Biology. 2004. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "hyperthyroidism." A Dictionary of Biology. 2004. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O6-hyperthyroidism.html "hyperthyroidism." A Dictionary of Biology. 2004. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O6-hyperthyroidism.html |
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hyperthyroidism
hyperthyroidism see thyroid gland . |
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"hyperthyroidism." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "hyperthyroidism." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1E1-X-hyperthy.html "hyperthyroidism." The Columbia Encyclopedia, 6th ed.. 2011. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1E1-X-hyperthy.html |
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hyperthyroidism
hyperthyroidism See thyrotoxicosis.
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DAVID A. BENDER. "hyperthyroidism." A Dictionary of Food and Nutrition. 2005. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. DAVID A. BENDER. "hyperthyroidism." A Dictionary of Food and Nutrition. 2005. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O39-hyperthyroidism.html DAVID A. BENDER. "hyperthyroidism." A Dictionary of Food and Nutrition. 2005. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O39-hyperthyroidism.html |
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