Rheumatoid Factor
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Contents |
More Specific Terms
Reference-interval
- < 40 IU/L
Principle
- rheumatoid factor is anti IgG Fc:
- immunoglobulin directed against the Fc portion of IgG
- RF is often polyreactive with binding to nuclear components as well as IgG
- generally RF is of the IgM class, but IgA & IgG RFs have been described. RF
Clinical-significance
- RF may be found in synovial fluid & pleural effusions as well as serum
- RF is not specific for rheumatoid arthritis, regardless of source
- 10% of normal elderly individuals are positive for RF
- cyclic citrullinated peptide antibody is a good marker for RA in patients with other disorders also associated with positive RF
Increases
- Disorders associated with rheumatoid factor: [2]
- disorders most likely to have high titers
- rheumatoid arthritis (80%, 50% in elderly)
- often negative in early phases of RA
- disorders with low titers
- systemic lupus erythematosus
- scleroderma ( systemic sclerosis)
- mixed connective tissue disease
- sarcoidosis
- idiopathic pulmonary fibrosis
- hypergammaglobulinemic purpura
- asbestosis
- malignancies
- infectious mononucleosis
- influenza
- chronic active hepatitis (B & C)
- vaccinations
- tuberculosis
- syphilis
- Brucellosis
- Leprosy
- Salmonellosis
- Malaria
- Kala-azar
- Schistosomiasis
- Filariasis
- Trypanosomiasis
- rubella
Methods
- agglutination of latex particles coated with IgG
- nephelometry
More General Terms
Additional Terms
- endocarditis
- mixed cryoglobulinemia
- rheumatoid arthritis (RA)
- Sjogren's syndrome (keratoconjunctivitis sicca, autoimmune epitheliitis)
References
- Clinical Diagnosis & Management by Laboratory Methods, 19th edition, J.B. Henry (ed), W.B. Saunders Co., Philadelphia, PA. 1996, pg 471, 475, 1019
- Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 826
- Medical Knowledge Self Assessment Program (MKSAP) 11, American College of Physicians, Philadelphia 1998
