MLT GlobeRheumatoid factor (RF)
Arthritis & Autoimmune · also called RA factor, RA test
What it measures
Measures autoantibodies (mostly IgM) against the Fc portion of IgG. It supports diagnosis and prognosis of rheumatoid arthritis but is not specific.
Specimen and preparation
- Specimen: Serum
- Tube: Gold top
Reference range
| Group | Range |
|---|---|
| Adult | < 14 (lab dependent, < 20) IU/mL |
Reference ranges differ between laboratories, methods and populations. Always use the range printed on your own lab report.
Causes of high values
- Rheumatoid arthritis (about 70–80%)
- Sjögren syndrome, SLE, mixed cryoglobulinemia
- Chronic infections: hepatitis C, endocarditis, TB
- Healthy older adults
Method
Immunoturbidimetry/nephelometry; latex agglutination
Good to know
High titres predict more erosive disease; combine with anti-CCP for better specificity.
Related tests
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