What is RF IgM?
the classic rheumatism marker
Rheumatoid factor is the classic marker for rheumatoid arthritis. It is less specific than anti-CCP and can be positive in other autoimmune diseases.
Positive RF also appears in Sjögren's syndrome, chronic hepatitis, and in some healthy older people.
Test facts
- Unit
- IE/mL
- Sample
- Serum
- Fasting
- No fasting needed
- Turnaround
- 2 days
What does low RF IgM mean?
Negative RF makes RA less likely but does not rule out the disease.
What does high RF IgM mean?
Positive RF is interpreted alongside anti-CCP, joint symptoms, and the rest of the panel.
More markers in the same area
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This is general information about the marker, not an assessment of your values and not medical advice. Last updated: May 2026.