{{Infobox medical condition (new) | name = Selenium deficiency | synonyms = | image = Se-TableImage.svg | caption = Selenium | pronounce = | field = | symptoms = | complications = | onset = | duration = | types = | causes = compromised intestinal function | risks = | diagnosis = | differential = | prevention = | treatment = | medication = | prognosis = | frequency = | deaths = }} '''Selenium deficiency''' occurs when an organism lacks the required levels of selenium, a critical nutrient in many species. Deficiency, although relatively rare in healthy well-nourished individuals,<ref>{{cite journal |last1=Weeks |first1=Benjamin S. |last2=Hanna |first2=Mirna S. |last3=Cooperstein |first3=Deborah |title=Dietary selenium and selenoprotein function |journal=Medical Science Monitor |date=2012 |volume=18 |issue=8 |pages=RA127–RA132 |doi=10.12659/msm.883258 |pmid=22847213 |pmc=3560698 }}</ref> can have significant negative results,<ref>{{cite journal |last1=Kieliszek |first1=Marek |title=Selenium–Fascinating Microelement, Properties and Sources in Food |journal=Molecules |date=3 April 2019 |volume=24 |issue=7 |page=1298 |doi=10.3390/molecules24071298 |pmid=30987088 |pmc=6480557 |doi-access=free }}</ref> affecting the health of the heart and the nervous system; contributing to depression, anxiety, and dementia; and interfering with reproduction and gestation.
==Signs and symptoms== Selenium deficiency in combination with Coxsackievirus infection can lead to Keshan disease, which is potentially fatal. Selenium deficiency also contributes (along with iodine deficiency) to Kashin-Beck disease.<ref name=":0">{{Cite web|url = http://www.atsdr.cdc.gov/toxprofiles/tp92-c3.pdf|title = Toxicological Profile for Selenium|date = September 2003|access-date = 7 Sep 2015|website = Agency for Toxic Substances and Disease Registry|publisher = U.S. Department of Health and Human Services}}</ref> The primary symptom of Keshan disease is myocardial necrosis, leading to the weakening of the heart. Kashin-Beck disease results in atrophy, degeneration, and necrosis of cartilage tissue.<ref>{{cite journal |doi=10.1056/NEJM199810153391604 |title=Kashin–Beck Osteoarthropathy in Rural Tibet in Relation to Selenium and Iodine Status |year=1998 |last1=Moreno-Reyes |first1=Rodrigo |last2=Suetens |first2=Carl |last3=Mathieu |first3=Françoise |last4=Begaux |first4=Françoise |last5=Zhu |first5=Dun |last6=Rivera |first6=Maria T. |last7=Boelaert |first7=Marleen |last8=Nève |first8=Jean |last9=Perlmutter |first9=Noémi |last10=Vanderpas |first10=Jean |s2cid=2485235 |journal=New England Journal of Medicine |volume=339 |issue=16 |pages=1112–20 |pmid=9770558 |display-authors=8 |doi-access=free }}</ref> Keshan disease also makes the body more susceptible to illness caused by other nutritional, biochemical, or infectious diseases.
Selenium is also necessary for the conversion of the thyroid hormone thyroxine (T4) into its more active counterpart triiodothyronine (T3),<ref name=":0" /> and as such a deficiency can cause symptoms of hypothyroidism, including extreme fatigue, mental slowing, goiter, cretinism, and recurrent miscarriage.<ref name="ODS Selenium">{{cite web |title=Selenium |url=https://ods.od.nih.gov/factsheets/selenium-HealthProfessional/ |website=Office of Dietary Supplements }}</ref>
==Causes== It can occur in patients with severely compromised intestinal function, those undergoing total parenteral nutrition, those who have had gastrointestinal bypass surgery, and also in persons of advanced age (i.e., over 90).<ref>{{cite journal |first1=Giovanni |last1=Ravaglia |first2=Paola |last2=Forti |first3=Fabiola |last3=Maioli |first4=Luciana |last4=Bastagli |first5=Andrea |last5=Facchini |first6=Erminia |last6=Mariani |first7=Lucia |last7=Savarino |first8=Simonetta |last8=Sassi |first9=Domenico |last10=Lenaz |first10=G |last9=Cucinotta |title=Effect of micronutrient status on natural killer cell immune function in healthy free-living subjects aged ≥90 y |journal=American Journal of Clinical Nutrition |pmid=10648276 |year=2000 |volume=71 |issue=2 |pages=590–8|display-authors=8 |doi=10.1093/ajcn/71.2.590 |doi-access=free }}</ref>
People dependent on food grown from selenium-deficient soil may be at risk for deficiency.{{citation needed|date=July 2023}} Increased risk for developing various diseases has also been noted, even when certain individuals lack optimal amounts of selenium, but not enough to be classified as deficient.{{Citation needed|date=September 2017}}
For some time now, it has been reported in the medical literature that a pattern of side effects possibly associated with cholesterol-lowering drugs (e.g., statins) may resemble the pathology of selenium deficiency.<ref>{{cite journal |pmid=15031036 |year=2004 |last1=Moosmann |first1=B |last2=Behl |first2=C |s2cid=43675310 |title=Selenoprotein synthesis and side-effects of statins |volume=363 |issue=9412 |pages=892–4 |doi=10.1016/S0140-6736(04)15739-5 |journal=Lancet}}</ref><ref>{{cite journal |pmid=15542379 |year=2004 |last1=Moosmann |first1=B |last2=Behl |first2=C |title=Selenoproteins, cholesterol-lowering drugs, and the consequences: Revisiting of the mevalonate pathway |volume=14 |issue=7 |pages=273–81 |doi=10.1016/j.tcm.2004.08.003 |journal=Trends in Cardiovascular Medicine}}</ref>
==Diagnosis== ===Reference ranges=== The European Food Safety Authority (EFSA) recommends a dietary allowance of 70 μg per day selenium intake for adults.<ref name=":1">{{Cite journal|date=2021-09-01|title=Selenium stimulates the antitumour immunity: Insights to future research|journal=European Journal of Cancer|language=en|volume=155|pages=256–267|doi=10.1016/j.ejca.2021.07.013|issn=0959-8049|doi-access=free|last1=Razaghi|first1=Ali|last2=Poorebrahim|first2=Mansour|last3=Sarhan|first3=Dhifaf|last4=Björnstedt|first4=Mikael|pmid=34392068}}</ref> In the US, the Dietary Reference Intake for adults is 55 μg/day. In the UK it is 75 μg/day for adult males and 60 μg/day for adult females. The 55 μg/day recommendation is based on the full expression of plasma glutathione peroxidase. Selenoprotein P<ref name="pmid17508906">{{cite journal |doi=10.1089/ars.2007.1528 |title=From Selenium to Selenoproteins: Synthesis, Identity, and Their Role in Human Health |year=2007 |last1=Papp |first1=Laura Vanda |last2=Lu |first2=Jun |last3=Holmgren |first3=Arne |last4=Khanna |first4=Kum Kum |journal=Antioxidants & Redox Signaling |volume=9 |issue=7 |pages=775–806 |pmid=17508906|s2cid=38176932 |url=http://pdfs.semanticscholar.org/8611/8b8c1a6149e0e22d6184bf59ee2b446563e5.pdf |archive-url=https://web.archive.org/web/20190228042314/http://pdfs.semanticscholar.org/8611/8b8c1a6149e0e22d6184bf59ee2b446563e5.pdf |url-status=dead |archive-date=2019-02-28 }}</ref> is a better indicator of selenium nutritional status, and full expression of it would require more than 66 μg/day.<ref name="pmid15817859">{{cite journal |last1=Xia |first1=Yiming |last2=Hill |first2=Kristina E |last3=Byrne |first3=Daniel W |last4=Xu |first4=Jiayuan |last5=Burk |first5=Raymond F |title=Effectiveness of selenium supplements in a low-selenium area of China |journal=The American Journal of Clinical Nutrition |date=1 April 2005 |volume=81 |issue=4 |pages=829–834 |doi=10.1093/ajcn/81.4.829 |pmid=15817859 |doi-access=free }}</ref>
==Epidemiology and prevention== Selenium deficiency is uncommon, but regions in China, Europe, Russia, and New Zealand have low selenium levels in croplands and diet.<ref name=":1" /> The worldwide prevalence of selenium deficiency is however predicted to rise under climate change due to the loss of selenium from croplands.<ref name=":1" /> These diseases are most common in certain parts of China where the intake is low<ref name="urlSelenium: Mineral Deficiency and Toxicity: Merck Manual Professional">{{cite web |last1=Johnson |first1=Larry E. |title=Selenium Deficiency |url=https://www.merckmanuals.com/professional/nutritional-disorders/mineral-deficiency-and-toxicity/selenium-deficiency |website=Merck Manuals Professional Edition |date=May 2020 }}</ref> because the soil is extremely deficient in selenium. Studies in Jiangsu Province of China have indicated a reduction in the prevalence of these diseases by taking selenium supplements.<ref name="ODS Selenium"/> In Finland, selenium salts are added to chemical fertilizers, as a way to increase selenium in soils.<ref>{{cite journal |last1=Varo |first1=P |last2=Alfthan |first2=G |last3=Ekholm |first3=P |last4=Aro |first4=A |last5=Koivistoinen |first5=P |title=Selenium intake and serum selenium in Finland: effects of soil fertilization with selenium |journal=The American Journal of Clinical Nutrition |date=1 August 1988 |volume=48 |issue=2 |pages=324–329 |doi=10.1093/ajcn/48.2.324 |pmid=2841842 }}</ref> Dietary supplements may utilize sodium selenite, L-selenomethionine, or selenium-enriched yeast.
==In animals== In some regions (e.g. much of the northeastern and northwestern US and adjacent Canada, and the southeastern US), selenium deficiency in some animal species is common unless supplementation is carried out.<ref name=NRCsheep1985>{{cite book |title=Nutrient Requirements of Sheep |url=https://books.google.com/books?id=hcbPz4AfdoEC |date=1985 |publisher=National Academies Press |isbn=978-0-309-03596-5 |edition=6th}}</ref> Selenium deficiency is responsible (either alone or together with vitamin E deficiency) for many of the cases of WMD ("white muscle disease"), evidenced at slaughter or during necropsy by the whitish appearance of striated muscle tissue due to bleaching by peroxides and hydroperoxides.<ref>{{cite book |last1=Jensen |first1=Rue |last2=Swift |first2=Brinton L. |last3=Kimberling |first3=Cleon V. |title=Jensen and Swift's Diseases of Sheep |date=1988 |publisher=Lea & Febiger |isbn=978-0-8121-1099-9 }}{{page needed|date=August 2020}}</ref> Although this degenerative disease can occur in foals, pigs, and other animal species, ruminants are particularly susceptible.<ref>{{cite book |last1=Underwood |first1=Eric John |title=The Mineral Nutrition of Livestock |date=1999 |publisher=CABI |isbn=978-0-85199-128-3 }}{{page needed|date=August 2020}}</ref> In general, absorption of dietary selenium is lower in ruminants than in non-ruminants and lower from forages than from grain.<ref name=NRCsr2007>{{cite book |author=Committee on the Nutrient Requirements of Small Ruminants |title=Nutrient Requirements of Small Ruminants: Sheep, Goats, Cervids, and New World Camelids |url=https://books.google.com/books?id=1FZOX5oQ7MUC&pg=PA1 |date=2007 |publisher=National Academies Press |isbn=978-0-309-10213-1 }}{{page needed|date=August 2020}}</ref> Sheep are more susceptible than cattle to WMD, and goats are more susceptible than sheep.<ref name=NRCsr2007/> Because of selenium's role in certain peroxidases (converting hydroperoxides to alcohols) and because of the antioxidant role of vitamin E (preventing hydroperoxide formation), a low level of Se can be somewhat (but not wholly) compensated by a high level of vitamin E. (In the animal, localization of peroxidases and vitamin E differs, partly because of the fat-solubility of vitamin E.) Some studies have indicated that about 0.12 or 0.23 mg Se per kg of dry matter intake may be sufficient for avoiding Se deficiency in sheep.<ref name=NRCsheep1985/> However, a somewhat higher Se intake may be required to avoid WMD where certain legumes are consumed.<ref>{{cite journal |last1=Whanger |first1=P. D. |first2=P. H. |last2=Weswig |first3=J. E. |last3=Oldfield |first4=P. R. |last4=Cheeke |first5=O. H. |last5=Muth |year=1972 |title=Factors influencing selenium and white muscle disease: forage types, salts, amino acids, and dimethyl sulfoxide |journal=Nutr. Rep. Int |volume=6 |pages=21–37 }}</ref> The cyanogenic glycosides in some white clover (''Trifolium repens'') varieties may influence the Se requirement,<ref name=NRCsr2007/> presumably because of cyanide from the aglycone released by glucosidase activity in the rumen<ref>{{cite journal |last1=Coop |first1=I. E. |first2=R. L. |last2=Blakely |year=1949 |title=The metabolism and toxicity of cyanides and cyanogenic glycosides in sheep |journal=N. Z. J. Sci. Technol |volume=30 |pages=277–291 |url=https://www.cabdirect.org/cabdirect/abstract/19511401240}}</ref> and inactivation of glutathione peroxidases by the effect of absorbed cyanide on the glutathione moiety.<ref>{{cite journal |last1=Kraus |first1=Richard J. |last2=Prohaska |first2=Joseph R. |last3=Ganther |first3=Howard E. |title=Oxidized forms of ovine erythrocyte glutathione peroxidase cyanide inhibition of a 4-glutathione:4-selenoenzyme |journal=Biochimica et Biophysica Acta (BBA) - Enzymology |date=September 1980 |volume=615 |issue=1 |pages=19–26 |doi=10.1016/0005-2744(80)90004-2 |pmid=7426660 }}</ref>
In areas where selenium deficiency in livestock is a concern, selenium (as selenite) may be supplemented in feed. Certain countries, e.g., the US and Canada, regulate such supplementation. Neonate ruminants at risk of WMD may be administered both Se and vitamin E by injection; some of the WMD myopathies respond only to Se, some only to vitamin E, and some to either.<ref>{{cite book |editor-first=Cynthia M. |editor-last=Kahn |title=The Merck Veterinary Manual |url=https://books.google.com/books?id=5UZjngEACAAJ |date=2005 |publisher=Wiley |edition=9th |isbn=978-0-911910-50-6}}{{page needed|date=August 2020}}</ref>
==References== {{Reflist}}
== External links == {{Medical resources | DiseasesDB = 11941 | ICD10 = {{ICD10|E|59||e|50}} | ICD9 = {{ICD9|269.3}} | ICDO = | OMIM = | MedlinePlus = | eMedicineSubj = | eMedicineTopic = | MeshID = }} {{Nutritional pathology}}
Category:Mineral deficiencies Category:Selenium