Editing Hyperthyroidism (section)

==Causes==
[[File:Causes of hyperthyroidism.png|thumb|Most common causes of hyperthyroidism by age.<ref>{{cite journal | vauthors = Carlé A, Pedersen IB, Knudsen N, Perrild H, Ovesen L, Rasmussen LB, Laurberg P | title = Epidemiology of subtypes of hyperthyroidism in Denmark: a population-based study | journal = European Journal of Endocrinology | volume = 164 | issue = 5 | pages = 801–809 | date = May 2011 | pmid = 21357288 | doi = 10.1530/EJE-10-1155 | s2cid = 25049060 | doi-access = free }}</ref>]]
There are several causes of hyperthyroidism. Most often, the entire gland is overproducing thyroid hormone. Less commonly, a single nodule is responsible for the excess hormone secretion, called a "hot" nodule. Thyroiditis (inflammation of the thyroid) can also cause hyperthyroidism.<ref>{{cite web |url=http://www.endocrineweb.com/hyper2.html |title=Hyperthyroidism Overview |access-date=2010-04-27 |url-status=live |archive-url=https://web.archive.org/web/20100428091701/http://www.endocrineweb.com/hyper2.html |archive-date=28 April 2010}}</ref> Functional thyroid tissue producing an excess of thyroid hormone occurs in a number of clinical conditions.

The major causes in humans are:
* [[Graves' disease]]. An autoimmune disease (usually, the most common cause with 50–80% worldwide, although this varies substantially with location- i.e., 47% in Switzerland (Horst et al., 1987) to 90% in the USA (Hamburger et al. 1981)). Thought to be due to varying levels of iodine in the diet.<ref name="AnderssonZimmermann2010">{{cite book | vauthors = Andersson M, Zimmermann MB |title=Thyroid Function Testing |chapter=Influence of Iodine Deficiency and Excess on Thyroid Function Tests |volume=28 |year=2010 |pages=45–69 |issn=1566-0729 |doi=10.1007/978-1-4419-1485-9_3 |series=Endocrine Updates |isbn=978-1-4419-1484-2 }}</ref> It is eight times more common in females than males and often occurs in young females, around 20 to 40 years of age.<ref>{{Cite web |last=Services |first=Department of Health & Human |title=Thyroid - hyperthyroidism |url=https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/thyroid-hyperthyroidism |access-date=2025-05-23 |website=www.betterhealth.vic.gov.au |language=en}}</ref>
* [[Toxic thyroid adenoma]] (the most common cause in Switzerland, 53%, thought to be atypical due to a low level of dietary iodine in this country)<ref name="AnderssonZimmermann2010" />
* [[Toxic multinodular goiter]]{{cn|date=July 2024}}
High blood levels of thyroid hormones (most accurately termed [[hyperthyroxinemia]]) can occur for a number of other reasons:
* [[Inflammation]] of the thyroid is called [[thyroiditis]]. There are several different kinds of thyroiditis including [[Hashimoto's thyroiditis]] (Hypothyroidism immune-mediated), and [[subacute thyroiditis]] (de Quervain's). These may be ''initially'' associated with secretion of excess thyroid hormone but usually progress to gland dysfunction and, thus, to hormone deficiency and hypothyroidism.
* Oral consumption of excess thyroid hormone tablets is possible (surreptitious use of thyroid hormone), as is the rare event of eating ground beef or pork contaminated with thyroid tissue, and thus thyroid hormones (termed ''hamburger thyrotoxicosis'' or ''alimentary thyrotoxicosis'').<ref>{{cite journal | vauthors = Parmar MS, Sturge C | title = Recurrent hamburger thyrotoxicosis | journal = CMAJ | volume = 169 | issue = 5 | pages = 415–417 | date = September 2003 | pmid = 12952802 | pmc = 183292 }}</ref> Pharmacy compounding errors may also be a cause.<ref name="pmid25762821">{{cite journal | vauthors = Bains A, Brosseau AJ, Harrison D | title = Iatrogenic thyrotoxicosis secondary to compounded liothyronine | journal = The Canadian Journal of Hospital Pharmacy | volume = 68 | issue = 1 | pages = 57–9 | date = 2015 | pmid = 25762821 | pmc = 4350501 | doi = 10.4212/cjhp.v68i1.1426 }}</ref>
* [[Amiodarone]], an [[antiarrhythmic agent|antiarrhythmic drug]], is structurally similar to thyroxine and may cause either under-or [[Amiodarone induced thyrotoxicosis|overactivity]] of the thyroid.{{cn|date=July 2024}}
* [[Postpartum thyroiditis]] (PPT) occurs in about 7% of women during the year after they give birth. PPT typically has several phases, the first of which is hyperthyroidism. This form of hyperthyroidism usually corrects itself within weeks or months without the need for treatment.
* A [[struma ovarii]] is a rare form of monodermal [[teratoma]] that contains mostly thyroid tissue, which leads to hyperthyroidism.
* Excess iodine consumption notably from algae such as [[kelp]].

Thyrotoxicosis can also occur after taking too much thyroid hormone in the form of supplements, such as [[levothyroxine]] (a phenomenon known as exogenous thyrotoxicosis, [[Human gastrointestinal tract|alimentary]] thyrotoxicosis, or [[Occult (disambiguation)|occult]] factitial thyrotoxicosis).<ref name="emedicine.medscape">{{cite web | vauthors = Floyd JL | orig-date = 2009 | title = Thyrotoxicosis | work = eMedicine |url=http://emedicine.medscape.com/article/383062-overview |url-status=live |archive-url=https://web.archive.org/web/20100317115206/http://emedicine.medscape.com/article/383062-overview |archive-date=17 March 2010|date=2017-03-21 }}</ref>

Hypersecretion of [[thyroid stimulating hormone]] (TSH), which in turn is almost always caused by a [[pituitary adenoma]], accounts for much less than 1 percent of hyperthyroidism cases.<ref>{{cite web | url = http://www.uptodate.com/contents/thyrotropin-tsh-secreting-pituitary-adenomas | title = Thyrotropin (TSH)-secreting pituitary adenomas. | work = UpToDate | archive-url = https://web.archive.org/web/20110218143345/http://www.uptodate.com/contents/thyrotropin-tsh-secreting-pituitary-adenomas | archive-date=18 February 2011 | vauthors = Weiss RE, Refetoff S  | quote = Last literature review version 19.1: January 2011. This topic last updated: 2 July 2009 }}</ref>