The determination (by quantitative measurement) of the rheumatoid factor is used to diagnose and prognose rheumatoid arthritis.
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Rheumatoid factor, or more correctly rheumatoid factors (RF), are antibodies directed against the Fc portion of the immunoglobulin IgG. Although the IgM class is the most common class of rheumatoid factors, both IgG and IgA rheumatoid factors can be present.
Rheumatoid factor is present in serum in 50-95% of adults with rheumatoid arthritis. It occurs in serum and synovial fluid several months after the onset of the disease and is detected for years after treatment. Although this factor is not specific to rheumatoid arthritis, it is beneficial in diagnosis because high titers are associated with severe disease compared to other diseases. Analgesia and anti-inflammatory drugs do not affect the presence of rheumatoid factor.
According to the American Rheumatology Society, criteria for the diagnosis of rheumatoid arthritis include:
- Morning stiffness (lasting at least 1 hour before maximal improvement)
- Arthritis of 3 or more joints (concomitant with swelling of soft tissues or presence of fluid)
- Arthritis of the joints of the hand (wrist, metacarpophalangeal or phalanx joints)
- Symmetrical arthritis (concurrent involvement of the same joint on both sides of the body)
- Rheumatoid nodules (subcutaneous nodules over bone protrusions or extensor surfaces)
- Rheumatoid factor in serum (presence of abnormal rheumatoid factor in serum)
- Radiological lesions (typical of rheumatoid arthritis in hand and wrist radiographs)
Possible Interpretations of Pathological Values
- Increase: Allografts (skin, kidneys), ankylosing spondylitis, cancer, cirrhosis, dermatomyositis, diabetes mellitus, diseases (kidney, liver, lung), endocarditis, healthy individuals over 60 years of age, liver neoplasms, hepatitis, hypertension, infectious mononucleosis, juvenile rheumatoid arthritis, visceral leishmaniasis, leprosy, lymphomas, macroglobulinemia, malaria, mixed connective tissue disease, neuropathy, osteoarthritis, paraproteinemia, polyarteritis nodosa, interstitial pulmonary fibrosis, rheumatoid arthritis, sarcoidosis, schistosomiasis, scleroderma, Sjögren's syndrome, splenomegaly, subacute bacterial endocarditis, syphilis, systemic lupus erythematosus, transfusions (multiple), tuberculosis, vaccinations (multiple), vasculitis, viral infections
Important Note
Laboratory test results are the most critical parameter for diagnosing and monitoring all pathological conditions. Between 70 to 80% of diagnostic decisions are based on laboratory tests. Correctly interpreting laboratory results allows a doctor to distinguish "healthy" from "diseased."
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be analyzed based on each case and family history, clinical findings, and the results of other laboratory tests and information. Your physician should explain the importance of your test results.
At Diagnostiki Athinon, we answer any questions you may have about the test you perform in our laboratory and contact your doctor to ensure you receive the best possible medical care.
