Blood test
Rheumatoid Factor Test
A rheumatoid factor test measures an antibody often found in rheumatoid arthritis and some other autoimmune conditions.
Quick answer
Rheumatoid Factor Test: what it is and what the results mean
Rheumatoid factor (RF) is an antibody that can be measured in the blood. It is present in many people with rheumatoid arthritis and some other autoimmune and inflammatory conditions.
- Why it is done: It is used to help diagnose rheumatoid arthritis in people with joint pain, swelling and stiffness, and to investigate other autoimmune conditions such as Sjögren’s syndrome.
- Understanding results: A positive result supports rheumatoid arthritis, especially with typical symptoms, but some people with the disease test negative and some healthy people test positive.
What it is
Rheumatoid factor (RF) is an antibody that can be measured in the blood. It is present in many people with rheumatoid arthritis and some other autoimmune and inflammatory conditions.
Why it is done
It is used to help diagnose rheumatoid arthritis in people with joint pain, swelling and stiffness, and to investigate other autoimmune conditions such as Sjögren’s syndrome.
What to expect
It is a standard blood test from a vein in the arm, needing no special preparation. It is often checked together with anti-CCP antibodies and inflammatory markers.
Understanding the results
A positive result supports rheumatoid arthritis, especially with typical symptoms, but some people with the disease test negative and some healthy people test positive. Results are interpreted with symptoms and other tests.
Good to know
Risks and limitations
It is a safe blood test but is not specific to one disease. A negative RF does not rule out rheumatoid arthritis, and a positive RF alone does not diagnose it.
Education and reference only. This explains the test in general terms and is not medical advice. Always follow the specific instructions from the team arranging your test, and discuss your results with your clinician.
Answers
Rheumatoid Factor Test: frequently asked questions
Can I have rheumatoid arthritis with a negative rheumatoid factor?
Yes. A proportion of people with rheumatoid arthritis are “seronegative”, meaning their rheumatoid factor is negative. Diagnosis is based on symptoms, examination and other tests as well.
What is the difference between rheumatoid factor and anti-CCP?
Both are antibodies linked to rheumatoid arthritis, but anti-CCP is more specific to the disease. They are often measured together to improve diagnostic accuracy.
Related tests
Other blood test investigations
Sources
Where this is drawn from
- NHS — Tests and treatments
- NICE — diagnostic guidance
- Association for Laboratory Medicine / relevant professional body
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