Rheumatoid Factor Total Antibody (IgM)

Immunology

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Description

Rheumatoid factor ( RF ) is an autoantibody directed against the Fc portion of IgG that can be used as a marker of rheumatoid arthritis ( RA ). The most common and clinically useful class of RF is IgM, however there are also IgG and IgA forms. RF is not diagnostic of RA as 2-10% of the normal population will have a positive result [2]. 20-30% of patients with RA have no RF, this is referred to as �seronegative arthritis� [4]. In classic RA, higher titres are associated with systemic symptoms, vasculitis and more severe forms of the disease [3]. Current guidelines for the management and treatment of RA recommend that RF is the initial investigation that should be carried out on patients with suspected RA. If RF is negative but it is still likely that they have RA it is recommended that the patient is referred to a specialist for further investigations [1]. RF has been detected in patients with various connective tissue diseases such as Systemic Lupus Erythematosus ( SLE ) and Sj�gren's syndrome, and also in the sera of patients with hypergammaglobulinaemic liver disease, syphilis, sarcoidosis and transiently following infection [2].

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Indications

Polyarthritis, Rheumatoid Arthritis, Connective Tissue Disease, Cryoglobulinaemia.

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Sample Type

2mL Serum ( Gel 5mL Yellow tube ). Requests from outside Sheffield: Transport at ambient temperature via Royal Mail or Courier.

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Reference Range

0 - 15 IU/mL.Values less than 40 IU/mL may not be clinially significant.Reference range established by in-house validation.

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Turnaround Time

Within 3 days

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Testing Frequency

Daily

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References

Aletaha D, et al. 2010 Rheumatoid Arthritis classification criteria: An American College of Rheumatology/European League Against Rheumatism Collaborative Initiative. Arthritis and Rheumatism. 2010. 62( 9 ):2569-2581.NICE clinical guideline 79. Rheumatoid arthritis: The management of rheumatoid arthritis in adults. 2009. [Ref 1]PRU Handbook of Clinical Immunochemistry. 9th Edition. 2007. [Ref 2]Moore TJ. Rheumatoid factors. Clin Imm Newsletter. 1998. 18:89-96. [Ref 3]Bridges SL. Update on autoantibodies in rheumatoid arthritis. 2004. Curr Rheumatol Rep. 6( 5 ):343-350. [Ref 4]

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See Also

ANA, CCP

Please note: the above information is subject to change and we endeavour to keep this website up to date wherever necessary.