Rheumatoid Factor

Medical Author:

Rheumatoid factor facts

  • Rheumatoid factor is an antibody that is detectable in the blood of 80% of adults with rheumatoid arthritis.
  • Rheumatoid can be detected in the blood of normal individuals and of those with other autoimmune diseases that are not rheumatoid arthritis.
  • In people with rheumatoid arthritis, high levels of rheumatoid factor can indicate a tendency toward more aggressive disease and/or a tendency to develop rheumatoid nodules and rheumatoid lung disease.

What is rheumatoid factor?

Rheumatoid factor is an antibody that is measurable in the blood. Rheumatoid factor is actually an antibody that can bind to other antibodies. Antibodies are normal proteins in our blood that are important parts of our immune system. Rheumatoid factor is an antibody that is not usually present in the normal individual.

For what is the rheumatoid factor test used?

Rheumatoid factor is commonly used as a blood test for the diagnosis of rheumatoid arthritis. Rheumatoid factor is present in about 80% of adults (but a much lower proportion of children) with rheumatoid arthritis.

Medically Reviewed by a Doctor on 2/21/2014

Patient Comments

Viewers share their comments

Rheumatoid Factor - Testing Question: Did you test positive for rheumatoid factor? How did your treatment progress?