rheumatoid factor in serum
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Indications
- evaulation of suspected rheumatoid arthritis (RA)
Reference interval
- < 40 IU/L
- < 14 IU/mL ARUP laboratories[5]
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
- 70% sensitivity for RA, poor specificity
- RF negative RA may later convert to RF positive[3]
- RF may be found in synovial fluid & pleural effusions as well as serum
- 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
- elevated rheumatoid factor is associated with an increased risk of developing rheumatoid arthritis[8]
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
- Sjogren's syndrome
- mixed cryoglobulinemia
- subacute bacterial endocarditis
- rheumatoid arthritis (80%, 50% in elderly)
- 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
More specific terms
- rheumatoid factor IgA in serum
- rheumatoid factor IgG in serum
- rheumatoid factor IgM in serum
- rheumatoid factor in serum qualitative
- rheumatoid factor in serum quantitative
References
- ↑ Clinical Diagnosis & Management by Laboratory Methods, 19th edition, J.B. Henry (ed), W.B. Saunders Co., Philadelphia, PA. 1996, pg 471, 475, 1019
- ↑ 2.0 2.1 Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 826
- ↑ 3.0 3.1 Medical Knowledge Self Assessment Program (MKSAP) 11, 17. American College of Physicians, Philadelphia 1998, 2015
- ↑ Panel of 4 tests Laboratory Test Directory ARUP: http://www.aruplab.com/guides/ug/tests/0050119.jsp
- ↑ 5.0 5.1 Rheumatoid Factor Laboratory Test Directory ARUP: http://www.aruplab.com/guides/ug/tests/0050465.jsp
- ↑ Mini Panel of 2 tests: Rheumatoid Factor . Cyclic Citrullinated Peptide Ab, IgG Laboratory Test Directory ARUP: http://www.aruplab.com/guides/ug/tests/0000000.jsp
- ↑ Mini Panel of 2 tests: Rheumatoid Factor . Cyclic Citrullinated Peptide Ab, IgG Laboratory Test Directory ARUP: http://www.aruplab.com/guides/ug/tests/0000000.jsp
- ↑ 8.0 8.1 Nielsen SF et al. Elevated rheumatoid factor and long term risk of rheumatoid arthritis: A prospective cohort study. BMJ 2012 Sep 6; 345:e5244 PMID: https://www.ncbi.nlm.nih.gov/pubmed/22956589
Simard JF and Holmqvist M. Rheumatoid factor positivity in the general population. BMJ 2012 Sep 6; 345:e5841 PMID: https://www.ncbi.nlm.nih.gov/pubmed/22956591