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Rheumatoid Arthritis
Test CodeRA
Alias/See Also
Rheumatoid Factor
CPT Codes
86431
Preferred Specimen
Red, PST
Minimum Volume
0.5 mL
Other Acceptable Specimens
Lithium Heparin Plasma (green top) tube
Transport Container
Serum (gold top) tube or Lithium Heparin Plasma (green top) tube
Transport Temperature
Room Temperature or Refrigeration
Specimen Stability
Room Temperature - 1 day; Refrigerated - 3 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Quantity Not Sufficient, IV contamination
Methodology
Photometric
Setup Schedule
Daily upon receipt
Report Available
Upon completion of analysis
Limitations
Pathologically high levels of IgG (>2500 mg/dL) may interfere with quantitation of RF.
Reference Range
< 12 IU/mL
Clinical Significance
Rheumatoid factor (RF) consists of autoantibodies of immunoglobulin isotypes IgM, IgA, IgG, and IgE. The function of RF remains unclear, but it may play a role in the regulation of humoral and cellular immunity and protection against invading microorganisms. Most patients with rheumatoid arthritis and Sjögren’s syndrome have elevated levels of RF. RF may also be elevated in scleroderma, dermatomyositis, Waldenström’s disease, sarcoidosis, and systemic lupus erythematosus. There are also instances of elevated RF without apparent disease or definable clinical disorders.