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My Rheumatologist Ordered A Rheumatoid Factor- What Is That? There are 4 main antibodies in the blood. They are IgG, IgM, IgA, including IgE. a particular antibody is a protein made by white blood cells. The purpose of a particular antibody is to fight off infections including to destroy any other invaders that should do harm. For example, say, you obtain a splinter. Your white blood cells rush to that area including mount a particular acute inflammatory response. Antibodies are produced to attack bacteria. The area around the splinter becomes swollen, red, including hurts. Your immune system is doing its job. Sometimes, though, a user should develop a particular autoimmune disease, meaning a disease where antibodies are created that are abnormal including are directed against the bodies own tissues. the creates a situation where there is chronic ongoing inflammation. The inflammation doesn’t shut off. the inflammation eventually causes damage to the body. Rheumatoid arthritis (RA) is a particular autoimmune disease. 1 pertaining to the first abnormalities in RA is the creation of rheumatoid factor. The rheumatoid factor (RF) is a particular antibody directed against another antibody called IgG. Most often the rheumatoid factor antibody is a particular IgM antibody. Sometimes it should be a particular IgA or a particular IgG. The level of rheumatoid factor should be measured using a specific blood test. The RF is not diagnostic for rheumatoid arthritis though. Patients with early RA should be negative for rheumatoid factor. Between 10 including 20% of patients could be persistently negative for rheumatoid factor throughout their illness. However, between 80-90% of patients with RA could be positive for RF at some time during the course of their disease. While RF by itself is not diagnostic of RA, it is 1 of many criteria used to help with making the diagnosis. The level of RF is additionally a good prognostic indicator since high levels of RF are associated with increased disease severity, the development of erosions (damage to the joint), involvement of other organ systems, including disability. RF is not specific for RA including should be found in patients with other diseases such as systemic lupus erythematosus, spondyloarthropathy, inflammatory muscle disease, viral infections, vasculitis, reactive arthritis, mixed cryoglobulinemia, sarcoidosis, bacterial endocarditis, syphilis, including leprosy. RF should additionally be present in older people who have absolutely no other illnesses. A more specific test for rheumatoid arthritis that is often ordered including the RF is the anti-cyclic citrullinated peptide antibody (anti-CCP). The anti-CCP is probably less sensitive than the RF so both tests probably should be ordered at the same time. The anti-CCP should be negative in patients with RA, so it’s important to look at the big picture rather than focus on the results of 1 test. Finally, since RF may be IgG, IgM, or IgA, it’s important to look for all 3 of these RFs. A note of caution...most laboratories only look for IgM rheumatoid factor. Make sure your rheumatologist looks for all three.
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