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Definition
By Mayo Clinic staffA rheumatoid factor test measures the amount of rheumatoid factor in your blood. Rheumatoid factors are autoantibodies — proteins produced by your immune system that can attack healthy tissue in your body. It's not clear what causes your immune system to produce rheumatoid factor. High levels of rheumatoid factor in the blood are most often associated with autoimmune diseases such as rheumatoid arthritis and Sjogren's syndrome. But rheumatoid factor may be detected in some healthy people, and people with autoimmune diseases sometimes have normal levels of rheumatoid factor.
Why it's done
References
- Shmerling RH. Origin and utility of measurement of rheumatoid factors. http://www.uptodate.com/home/index.html. Accessed Sept. 2, 2008.
- Tighe H, et al. Rheumatoid factor. In: Harris ED, et al. Kelley's Textbook of Rheumatology. 7th ed. Philadelphia, Pa.: Saunders Elsevier; 2005. http://www.mdconsult.com/das/book/body/103645283-2/0/1257/0.html. Accessed Sept. 2, 2008.
- Rheumatoid factor. Lab Tests Online. http://www.labtestsonline.org/understanding/analytes/rheumatoid/multiprint.html. Accessed Sept. 8, 2008.
- Chang-Miller A (expert opinion). Mayo Clinic, Scottsdale/Phoenix, Ariz. Sept. 20, 2008.
