All tests
Blood tests
Rheumatoid Factor (RF)
An antibody found in many people with rheumatoid arthritis, and in some people without it.
Video lesson
Why it’s ordered
To help diagnose RA and Sjögren’s disease.
Understanding results
About 70 to 80% of people with RA are positive. RF can also be positive in healthy older adults, hepatitis C, and other autoimmune or chronic diseases, so it’s interpreted with your symptoms.
Good to know
High levels go along with a higher chance of joint damage and RA outside the joints.
At a glance
Type
Blood tests
Reviewed by Farhan Tahir, MD, FACR
Questions about your own care?
Book an in-person or telehealth consultation with Dr. Tahir.
For education only. Don’t start, stop or change a medicine without talking to your care team.