Rheumatoid factor is an antibody that is detectable in the blood of approximately 80% of adults with rheumatoid arthritis.
The normal range for rheumatoid factor is less than 14 IU/ml. Any result with values 14 IU/ml or above is considered abnormally high, elevated, or positive.
High levels of rheumatoid factor may indicate:
- Rheumatoid arthritis (RA)
- Rheumatoid nodules
- Rheumatoid lung disease
It should be noticed that a negative RF test does not rule out RA. About 20% of people with RA will have very low levels of or no detectable RF.
Keywords: Rheumatoid Factor (RF)