A rheumatoid factor (RF) quantitative test measures the level of RF antibodies in blood—usually IgM—that are associated with rheumatoid arthritis. It helps diagnose and monitor disease activity; higher titers often correlate with more severe or persistent disease. A positive result supports but does not confirm RA, since RF can appear in other autoimmune or infectious conditions. Results are interpreted alongside clinical findings and other tests (e.g., anti‑CCP, CRP).

A normal rheumatoid factor (RF) in children is generally negative or very low. Most laboratory reference ranges consider an RF below about 14–20 IU/mL (commonly <15 IU/mL) as normal. Positive or higher values require clinical correlation and further evaluation, since ranges vary by lab and RF can be absent even in juvenile arthritis. Discuss results with a pediatrician or pediatric rheumatologist.

Costs vary: in the US typically $20–$150 out‑of‑pocket (often covered by insurance); in India about ₹200–₹800 at private labs; in the UK it’s usually free under the NHS or £20–£50 privately; Australia is often bulk‑billed or A$20–A$50 privately. Prices depend on lab, test panel, and whether insured or publicly funded—check your local provider.

A rheumatoid factor (RF) blood test detects antibodies that can indicate autoimmune joint disease. In children it helps support diagnosis of certain arthritis types (for example RF‑positive juvenile idiopathic arthritis) but is neither sensitive nor specific alone. Results are interpreted with symptoms, exam, imaging and other labs (ESR, CRP, anti‑CCP). The test is a simple blood draw; no special preparation is usually needed.

Elevated rheumatoid factor is most often seen with B‑cell and lymphoproliferative malignancies—especially non‑Hodgkin and Hodgkin lymphoma, chronic lymphocytic leukemia, Waldenström macroglobulinemia and multiple myeloma. RF can also be mildly raised in some solid tumors (lung, breast, pancreatic, liver) and with paraneoplastic immune responses, though less commonly than with hematologic cancers. Clinical context and further testing determine significance.

Early rheumatoid arthritis often causes joint pain, swelling, warmth and tenderness—typically symmetrically affecting small joints of the hands and feet. Morning stiffness lasting 30–60 minutes, reduced grip strength, and difficulty using affected joints are common. Systemic signs include persistent fatigue, low‑grade fever, loss of appetite and general malaise. Symptoms may be subtle at first and come and go.