The determination of rheumatoid factor is used for the diagnosis and prognosis of rheumatoid arthritis.
The rheumatoid factor, or more precisely the rheumatoid factor (RF), are antibodies directed against the Fc portion of the IgG immunoglobulin. Although IgM is the most common category of rheumatoid agents, both IgG and IgA rheumatoid agents may 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 rheumatoid arthritis and is detected for years after treatment. This factor, although not specific to rheumatoid arthritis, is very useful in diagnosis because high titers are associated with severe disease compared to titers in 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: Grafts (skin, kidneys), ankylosing spondylitis, cancer, cirrhosis, dermatomyositis, diabetes mellitus, diseases of the kidney, liver and lung, endocarditis, healthy individuals, 60 juvenile rheumatoid arthritis, visceral leishmaniasis, leprosy, lymphomas, macroglobulinemia, malaria, mixed connective tissue disease, neuropathy, osteoarthritis, paraproteinemia, nodular arthritis, interstitial pneumonitis, interstitial pneumonia stosomiasi, scleroderma, Sjögren syndrome splenomegaly, subacute bacterial endocarditis, syphilis, systemic lupus erythematosus, transfusions (multiplets), tuberculosis, vaccinations (multiplet), vasculitis, viral infections
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. Correct interpretation of 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 interpreted in relation to each individual case and family history, clinical findings and the results of other laboratory tests and information. Your personal 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 we contact your doctor to get the best possible medical care.