How are rheumatoid factors (RFs) findings interpreted?

Updated: Jan 28, 2021
  • Author: Tyler Street, MD; Chief Editor: Eric B Staros, MD  more...
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Rheumatoid factor (RF) is used in the diagnosis of rheumatoid arthritis (RA). RF results are positive in approximately 75% of patients with RA, although RF is not etiologically related to RA. [7]

High RF titers indicate a poorer prognosis, as patients with higher RF levels tend to have more severe disease. Patients with nodules or clinical evidence of vasculitis usually have positive RF results.

Low levels of RF can even be found in healthy patients, and the test is positive in up to 20% of older individuals. [4]

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