RA test Rheumatoid Arthritis factor test

The RA test detects rheumatoid factor (RF) — autoantibodies (most often IgM class) that target the Fc portion of human IgG. Older labs use a latex agglutination card test for qualitative positive/negative or semi-quantitative titre (1:20, 1:40, 1:80…). Modern labs increasingly use quantitative immunoassay (reported as IU/mL) — see the "Rheumatoid Factor (RF)" page for the quantitative version.

RF is positive in 60–80% of rheumatoid arthritis patients but is not specific to RA. It is also positive in Sjögren syndrome, chronic infections (hepatitis C, endocarditis, TB), other autoimmune diseases, and in 5–10% of healthy people over age 60.

Rheumatoid arthritis affects roughly 0.5–0.75% of Indian adults — a substantial burden, especially in women aged 30–60. Patients commonly present late after years of joint pain blamed on workload, age, or "gas" — by which time joint damage may already be visible on X-ray. Early diagnosis and DMARD therapy (methotrexate, hydroxychloroquine, sulfasalazine, leflunomide, biologics) can dramatically alter the disease course and prevent disability.

RA test (RF) is one of the standard antibody tests used alongside anti-CCP for diagnosis, classification (ACR/EULAR 2010 criteria), and prognosis. RF-positive RA tends to be more severe, more erosive, and more often associated with extra-articular manifestations (rheumatoid nodules, lung disease, vasculitis) than RF-negative RA. The qualitative RA test is widely available and inexpensive — useful for screening — but if positive, a quantitative RF and anti-CCP should follow.

No fasting required. Continue all medications including any DMARDs, steroids or biologics — these do not interfere meaningfully with RF testing. Mention recent infections (hepatitis C, endocarditis, TB) to your doctor for interpretation.