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Rheumatoid factor

General information

Specimen transport: At room temperature

Repeat frequency: At significant change of clinical symptoms

Special precautions: None

Laboratory information

Normal reference range: < 20 kIU/L

Volume and sample type: 7ml clotted blood

Method: Nephelometry

Turnaround time (calendar days from sample receipt to authorised result): Median - 1, 95th percentile - 5

Clinical information

Indications for the test: Aid for the prognosis of RA and Sjögren's syndrome in the presence of an erosive arthropathy.

Rheumatoid factor is not useful in the diagnosis of rheumatoid arthritis, it has a limited role in predicting the risk of complications particularly vasculitis.

Factors affecting the test: Disease activity: only 70-80% of patients with confirmed RA have positive rheumatoid factor. Detected in 2-10% of general population.

Elevated titres may also accompany a variety of acute immune responses particularly infections (50%), liver disease, Sarcoidosis, and SLE.


Clinical workstation reference: RH FACTOR


(Last updated October 7th 2014)