Editing Homocysteine (section)

==Homocysteine levels==

[[File:Plasma tHcy.svg|thumb|right|Total plasma homocysteine]]

Homocysteine levels typically are higher in men than women, and increase with age.<ref>{{cite journal|last=Nygård|first=O|author2=Vollset, SE |author3=Refsum, H |author4=Stensvold, I |author5=Tverdal, A |author6=Nordrehaug, JE |author7=Ueland, M |author8= Kvåle, G |title=Total plasma homocysteine and cardiovascular risk profile. The Hordaland Homocysteine Study|journal=JAMA: The Journal of the American Medical Association|date=Nov 15, 1995|volume=274|issue=19|pages=1526–33|pmid=7474221|doi=10.1001/jama.274.19.1526}}</ref><ref>{{cite journal|last=Refsum|first=H|author2=Nurk, E |author3=Smith, AD |author4=Ueland, PM |author5=Gjesdal, CG |author6=Bjelland, I |author7=Tverdal, A |author8=Tell, GS |author9=Nygård, O |author10= Vollset, SE |title=The Hordaland Homocysteine Study: a community-based study of homocysteine, its determinants, and associations with disease|journal=The Journal of Nutrition|date=June 2006|volume=136|issue=6 Suppl|pages=1731S–1740S|pmid=16702348|doi=10.1093/jn/136.6.1731S|doi-access=free}}</ref>

Common levels in Western populations are 10 to 12&nbsp;μmol/L, and levels of 20&nbsp;μmol/L are found in populations with low B-vitamin intakes or in the elderly (e.g., Rotterdam, Framingham).<ref>{{Cite journal|last1=Bots|first1=Michiel L.|last2=Launer|first2=Lenore J.|last3=Lindemans|first3=Jan|last4=Hoes|first4=Arno W.|last5=Hofman|first5=Albert|last6=Witteman|first6=Jacqueline C. M.|last7=Koudstaal|first7=Peter J.|last8=Grobbee|first8=Diederick E.|date=1999-01-11|title=Homocysteine and Short-term Risk of Myocardial Infarction and Stroke in the Elderly|journal=Archives of Internal Medicine|volume=159|issue=1|pages=38–44|doi=10.1001/archinte.159.1.38|pmid=9892328|issn=0003-9926|doi-access=free|hdl=1765/55858|hdl-access=free}}</ref><ref>{{Cite journal|last1=Selhub|first1=J.|last2=Jacques|first2=P. F.|last3=Bostom|first3=A. G.|last4=Wilson|first4=P. W.|last5=Rosenberg|first5=I. H.|date=2000|title=Relationship between plasma homocysteine and vitamin status in the Framingham study population. Impact of folic acid fortification|journal=Public Health Reviews|volume=28|issue=1–4|pages=117–145|issn=0301-0422|pmid=11411265}}</ref>

It is decreased with methyl folate trapping, where it is accompanied by decreased methylmalonic acid, increased folate, and a decrease in [[formiminoglutamic acid]].<ref>{{cite journal |last1=Scott |first1=JohnM. |last2=Weir |first2=DonaldG. |title=THE METHYL FOLATE TRAP: A physiological response in man to prevent methyl group deficiency in kwashiorkor (methionine deficiency) and an explanation for folic-acid-induced exacerbation of subacute combined degeneration in pernicious anaemia |journal=The Lancet |date=15 August 1981 |volume=318 |issue=8242 |pages=337–340 |doi=10.1016/S0140-6736(81)90650-4 |pmid=6115113 |s2cid=29977127 |issn=0140-6736}}</ref> This is the opposite of MTHFR C677T mutations, which result in an increase in homocysteine.{{citation needed|date=June 2019}}

{{anchor|ranges}}
{| class="wikitable"
 |+[[Reference ranges for blood tests|Blood reference ranges]] for homocysteine:
 |-
 |'''Sex'''||'''Age'''||'''Lower limit'''||'''Upper limit'''||'''Unit'''||'''Elevated'''||'''[[Optimal health range|Therapeutic target]]'''
 |- 
| rowspan =4| Female ||rowspan=2| 12–19 years || 3.3<ref name=doctorsdoctor>{{cite web|url=http://www.thedoctorsdoctor.com/labtests/homocysteine.htm|title=Homocysteine|website=www.thedoctorsdoctor.com|url-status=dead|archive-url=https://web.archive.org/web/20081205050029/http://www.thedoctorsdoctor.com/labtests/homocysteine.htm|archive-date=2008-12-05|access-date=2008-11-22}}</ref> || 7.2<ref name=doctorsdoctor/> || μmol/L ||rowspan=4| > 10.4 μmol/L <br /> or <br /> > 140 μg/dl  ||rowspan=8| < 6.3 μmol/L<ref name=adeeva>[http://www.adeeva.com/resources/bloodtestscomplete.html Adëeva Nutritionals Canada > Optimal blood test values] {{webarchive|url=https://web.archive.org/web/20090529032656/http://adeeva.com/resources/bloodtestscomplete.html |date=2009-05-29 }} Retrieved on July 9, 2009</ref> <br />or<br /> < 85 μg/dL<ref name=adeeva/> 
 |-
 | 45<ref name=homocysteine-molar>Derived from molar values using molar massof 135 g/mol</ref> || 100<ref name=homocysteine-molar/> || μg/dL
 |- 
| rowspan =2| >60 years || 4.9<ref name=doctorsdoctor/> || 11.6<ref name=doctorsdoctor/> ||μmol/L
 |-
 | 66<ref name=homocysteine-molar/> || 160<ref name=homocysteine-molar/> || μg/dL
 |- 
| rowspan =4| Male ||rowspan=2| 12–19 years || 4.3<ref name=doctorsdoctor/> || 9.9<ref name=doctorsdoctor/> || μmol/L ||rowspan=4| > 11.4 μmol/L <br /> or <br /> > 150 μg/dL
 |-
 | 60<ref name=homocysteine-molar/> || 130<ref name=homocysteine-molar/> || μg/dL
 |- 
| rowspan =2| >60 years || 5.9<ref name=doctorsdoctor/> || 15.3<ref name=doctorsdoctor/> ||μmol/L
 |-
 | 80<ref name=homocysteine-molar/> || 210<ref name=homocysteine-molar/> || μg/dL
 |-
 |}
The ranges above are provided as examples only; test results always should be interpreted using the range provided by the laboratory that produced the result.