Editing Rheumatoid factor (section)

==Interpretation==
High levels of rheumatoid factor (in general, above 20&nbsp;[[International unit|IU]]/mL, 1:40, or over the 95th [[percentile]]; there is some variation among labs) occur in rheumatoid arthritis (present in 80%) and [[Sjögren's syndrome]] (present in 50-70% of primary forms of disease).<ref name=sd49>[http://www.patient.co.uk/showdoc/40026049/ Rheumatoid Factor - Patient UK]</ref> The higher the level of RF the greater the probability of destructive articular disease.{{citation needed|date=September 2014}} It is also found in [[Epstein–Barr virus]] or [[Parvovirus]] infection and in 5–10% of healthy persons, especially the elderly.

There is an association between rheumatoid factor and more persistently active synovitis, more joint damage, greater eventual disability and [[arthritis]].<ref>[http://www.medicinenet.com/rheumatoid_factor/article.htm] {{full citation needed|date=November 2012}}</ref><ref>[http://www.arthriticassociation.org.uk/research/diet_arthritis_research_5 The Arthritis Association], Report by MHC 19.2</ref>

Other than in [[rheumatoid arthritis]], rheumatoid factor may also be elevated in other conditions, including:
* [[Systemic lupus erythematosus]] (SLE)<ref name="mayo">{{Cite web | url=https://www.mayoclinic.org/tests-procedures/rheumatoid-factor/about/pac-20384800 | title=Rheumatoid factor - Mayo Clinic| website=[[Mayo Clinic]]}}</ref><ref name=mnt>{{cite web | last=Johnson | first=Jon | title=Rheumatoid factor: Ranges, tests, and treatment | website=Medical News Today | date=21 July 2021 | url=https://www.medicalnewstoday.com/articles/325505 | access-date=13 May 2022}}</ref>
* [[Sjögren syndrome]]<ref name="mayo"/><ref name=mnt/>
* [[Hepatitis B]] and [[Hepatitis C|C]],<ref>{{Cite journal|date=2017-03-01|title=Vasculitic syndromes in hepatitis C virus: A review|journal=Journal of Advanced Research|language=en|volume=8|issue=2|pages=99–111|doi=10.1016/j.jare.2016.11.002|issn=2090-1232|doi-access=free|last1=Ragab|first1=Gaafar|last2=Hussein|first2=Mohamed A.|pmid=28149646|pmc=5272950}}</ref> [[herpes]], [[HIV]], and other viral infections<ref name=mnt/>
* [[Primary biliary cirrhosis]]<ref name=mnt/>
* [[Infectious mononucleosis]] and any chronic viral infection<ref name="mayo"/>
* [[Leprosy]]<ref>{{cite journal |last1=Garcia-De La Torre |first1=Ignacio|date=1993 |title=Autoimmune phenomena in leprosy, particularly antinuclear antibodies and rheumatoid factor. |journal=The Journal of Rheumatology |volume=20 |issue=5 |pages=900–3 |pmid=8336322 }}</ref>
* [[Sarcoidosis]]<ref name="mayo"/>
* [[Tuberculosis]], [[syphilis]] and other chronic bacterial infections<ref name=mnt/>
* [[Visceral leishmaniasis]]<ref>{{cite journal |last1=Atta |first1=AM |title=Serum markers of rheumatoid arthritis in visceral leishmaniasis: rheumatoid factor and anti-cyclic citrullinated peptide antibody. |journal= Journal of Autoimmunity|volume= 28|issue= 1|pages= 55–8|doi= 10.1016/j.jaut.2006.12.001|pmid=17257811 |year=2007 |url=http://repositorio.ufba.br/ri/handle/ri/14732 }}</ref>
* [[Malaria]] and other parasitic infections<ref name=mnt/>
* [[Cancer]]<ref name=mnt/>