Rheumatoid Factor (RF)
Immune blood
What It Is
Rheumatoid factor is an autoantibody found in the blood of many people with rheumatoid arthritis.
Why It Matters
RF helps support the diagnosis of rheumatoid arthritis, though it can also be elevated in other conditions.
If Levels Are High
Positive RF is seen in rheumatoid arthritis, Sjögren's syndrome, and other autoimmune conditions.
If Levels Are Low
Negative RF does not exclude rheumatoid arthritis (seronegative RA exists).
Preparation
No special preparation required.
How Often to Test
As clinically indicated.
Panels Including This Marker
Important Disclaimer
This information is for educational purposes only and does not constitute medical advice or diagnosis. Results should be interpreted in clinical context by a qualified healthcare professional. If you have severe symptoms or urgent concerns, seek urgent medical help.