1. RA factor is a protein (antibody) that is measurable in the blood with a routine blood test.
2. A positive RA factor test is mainly used as a supportive tool in making diagnosis of rheumatoid arthritis. Approximately, 70% of rheumatoid arthritis patients test positive for RA factor.
3. A negative RA factor test does not rule out the diagnosis of rheumatoid arthritis. Patients who test negative for RA factor but have signs and symptoms may still be diagnosed with rheumatoid arthritis. This is seen in around 30% patients with rheumatoid arthritis (seronegative).
4. There is no single test to diagnose rheumatoid arthritis. The diagnosis is made from a combination physical signs and medical history supported by various blood tests such as RA factor and anti-CCP.
5. The level of RA factor does not correlate with disease activity. It is not used for disease monitoring. If your test is positive then usually there is no need to repeat it again. Other lab tests such as ESR and CRP (Inflammatory markers) can be good markers to monitor treatment response.
6. Rheumatoid arthritis affects different patients in different ways. Rheumatoid arthritis patients with a positive RA factor test have the potential for a more aggressive disease course. Keep in mind this isn’t always the case. If RA factor is tested and symptoms are detected early, a diagnosis can be quickly reached. Treatment should be started as soon as possible to prevent joint damage.