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Rheumatoid factor quantitation
minimum sample volume required ~ 5ml
Special instructions
Minimum retesting interval: repeat testing is not routinely required (RCPath March 2021)
From 30/09/2024 RF assay is performed on Beckman AU analyser, accompanied with a change to the reference range/positivity threshold.
Reference range
<20
Units
IU/mL
Linked to
Rheumatoid factor screen
Turnaround Time
1
day
Department: Biochemistry
Clinical Application
RF testing can be used in conjunction with other laboratory and clinical findings, to aid in the diagnosis of rheumatoid arthritis (RA). However, in the absence of supportive symptoms or signs, RF testing is not a good screening test for rheumatic disease and a positive result in isolation should not be a reason for referral.
A positive result indicates the presence of RF IgM antibodies. RF positivity is seen in approximately 5% of the general population and rates are higher with increasing age, amongst other factors e.g. acute immune responses, liver disease, SLE.
For patients with symptoms and signs suggestive of rheumatoid arthritis or another connective tissue disease, consider discussion with, and/or referral to, the rheumatology team for further assessment, irrespective of the RF result.
Webpage updated: November 2024
