Rheumatoid Factor
Investigation : Rheumatoid Factor
Specimen type : Serum_or_Serum_Gel
Spec container : 5ml Clot Activator (GOLD) 
Reference range : See below IU/mL
Reference Intervals:

<14 IU/mL negative
≥ 14 IU/ mL positive

Clinical Interpretation

Rheumatoid factor is positive in 70-80% of adults with rheumatoid arthritis. A positive result can also be seen in a number of other conditions including: cryoglobulinemia (very high level), SLE, scleroderma, HIV and other infections, and also in 5% of normal healthy adults (low level).

A negative RF does not exclude rheumatoid arthritis. Where there is a strong clinical suspicion of rheumatoid arthritis disease, anti-CCP is a more appropriate test. Please send a new serum sample for CCP testing. In these patients, a negative result for RF should not delay referral to Rheumatology

RF has no value in monitoring of disease activity.

Additional information on rheumatoid factor and its clinical use can be found here: RF.


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