Indicator Explainer
Rheumatoid Factor
Antibodies in the serum of individuals with rheumatoid arthritis that react with antigenic determinants or immunoglobulins that enhance agglutination of suspended particles coated with pooled human gamma-globulin. Rheumatoid factors also occur in other autoimmune and certain infectious diseases.
This page explains what the indicator is and how results are interpreted in general terms. Reference ranges depend on the laboratory, the method, and your own situation — no single “normal value” applies to everyone. This page is health information, not a diagnosis. For symptoms, treatment, or urgent concerns, contact a healthcare professional.
When it is tested
Source: National Cancer Institute, NCI Thesaurus 26.09d, C805. NCI definition, reproduced without modification under CC BY 4.0. Source identity and definition checked automatically on 2026-10-18. No individual clinical interpretation or human reviewer is asserted.
Reading results
Reference intervals and interpretation depend on the laboratory, specimen, method and clinical context. This source definition is educational information; it does not establish a diagnosis, product approval or suitability for an individual.
Also Known As
References
- NCI Thesaurus 26.09d — Rheumatoid Factor (C805)
- Source: National Cancer Institute, NCI Thesaurus 26.09d, C805. NCI definition, reproduced without modification under CC BY 4.0.
- Preclinical and clinical outcomes in patients with high rheumatoid factor levels treated with TNF inhibitors:a systematic review. — Ann Rheum Dis, 2026-10-05 (PMID 42833948; literature)
- Why a positive rheumatoid factor test does not always mean rheumatoid arthritis. — J Clin Invest, 2026-10-01 (PMID 42820290; literature)
- Early rheumatoid factor decline predicts subsequent clinical remission in rheumatoid arthritis: the ANSWER cohort. — Rheumatology (Oxford), 2026-10-01 (PMID 42714931; literature)
- Interferon-driven gene signature identifies two distinct subgroups in rheumatoid factor-positive polyarticular juvenile idiopathic arthritis. — Rheumatology (Oxford), 2026-10-01 (PMID 42712152; literature)