Test guide
Rheumatoid Factor (RF) Test
A rheumatoid factor (RF) test checks a sample of your blood for rheumatoid factor, a protein made by the immune system .
What it is for
RF testing is mostly used with other tests to help diagnose rheumatoid arthritis. Rheumatoid arthritis (RA) is a type of autoimmune disorder that damages your joints and causes pain, swelling, and stiffness. It is a chronic (long-lasting) condition that can also affect your organs and cause other symptoms. An RF test can also be used to check for other autoimmune disorders, certain infections , and certain types of cancer . Source: MedlinePlus, National Library of Medicine. Medical test information is public domain. Source identity and definition checked automatically on 2026-10-18. No individual clinical interpretation or human reviewer is asserted.
Limitations
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
- RF Blood Test
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