Rheumatoid factor

A rheumatoid factor test measures the amount of rheumatoid factor in your blood. Rheumatoid factors are proteins produced by your immune system that can attack healthy tissue in your body.

High levels of rheumatoid factor in the blood are most often associated with autoimmune diseases, such as rheumatoid arthritis and Sjogren's syndrome. But rheumatoid factor may be detected in some healthy people, and people with autoimmune diseases sometimes have normal levels of rheumatoid factor.


Why it's done What you can expect Results

A rheumatoid factor test is one of a group of blood tests primarily used to help pinpoint a diagnosis of rheumatoid arthritis. These other tests may include:

  • Anti-nuclear antibody (ANA)
  • Anti-cyclic citrullinated peptide (anti-CCP) antibodies
  • C-reactive protein (CRP)
  • Erythrocyte sedimentation rate (ESR, or sed rate)

The amount of rheumatoid factor in your blood may also help your doctor choose the treatment approach that will work best for your situation.

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