Editing Congenital iodine deficiency syndrome (section)

==Cause==
[[File:Iodine_deficiency_world_map-DALYs_per_million_persons-WHO2012.svg|thumb|upright=1.2|[[:en:Disability-adjusted life year|Disability-adjusted life years]] (DALY) lost from iodine deficiency in 2012 in proportion to a million people
{{Div col|small=yes|colwidth=10em}}
{{legend|#ffff20|52–163}}
{{legend|#ffe820|181–217}}
{{legend|#ffd820|221–221}}
{{legend|#ffc020|222–310}}
{{legend|#ffa020|320–505}}
{{legend|#ff9a20|512–610}}
{{legend|#f08015|626–626}}
{{legend|#e06815|653–976}}
{{legend|#d85010|984–1,242}}
{{legend|#d02010|1,251–3,159}}
{{div col end}}]]
Around the world, the most common cause of congenital iodine deficiency syndrome (endemic cretinism)<ref name="icd.who.int">{{Cite web|url=https://icd.who.int/browse10/2019/en#/E00|title = ICD-10 Version:2019}}</ref> is dietary [[iodine deficiency]].

[[Iodine]] is an essential trace element, necessary for the synthesis of thyroid hormones. Iodine deficiency is the most common preventable cause of neonatal and childhood brain damage worldwide.<ref>{{cite journal |last1= Chen |first1= Zu-Pei |date= February 2010 |title= Cretinism Revisited |journal= Best Practice & Research Clinical Endocrinology & Metabolism  |volume= 24 |issue= 1|pages= 39–50|pmid= 20172469|doi= 10.1016/j.beem.2009.08.014|last2= Hetzel |first2= BS }}</ref> Although iodine is found in many foods, it is not universally present in all soils in adequate amounts. Most iodine, in iodide form, is in the oceans, where the iodide ions are reduced to elemental iodine, which then enters the atmosphere and falls to earth in rain, introducing iodine to soils. Soil deficient in iodine is most common inland, in mountainous areas, and in areas of frequent flooding. It can also occur in coastal regions, where iodine might have been removed from the soil by glaciation, as well as leaching by snow, water and heavy rainfall.<ref>[http://www.thyroidmanager.org/Chapter20/20-frame.htm Chapter 20. The Iodine Deficiency Disorders] {{webarchive|url=https://web.archive.org/web/20080313190009/http://www.thyroidmanager.org/Chapter20/20-frame.htm |date=2008-03-13 }} ''Thyroid Disease Manager''. Retrieved: 2011-06-26.</ref> Plants and animals grown in iodine-deficient soils are correspondingly deficient. Populations living in those areas without outside food sources are most at risk of iodine deficiency diseases.<ref>{{cite journal |vauthors=Gaitan E, Dunn JT |s2cid=43567038 |title=Epidemiology of iodine deficiency |journal=Trends Endocrinol. Metab. |volume=3 |issue=5 |pages=170–5 |year=1992 |pmid=18407097 |doi= 10.1016/1043-2760(92)90167-Y}}</ref>