A rheumatoid factor (RF) test measures the amount of rheumatoid factor (RF) in your blood. Rheumatoid factors are proteins produced by the immune system. ... An RF test is most often used to help diagnose rheumatoid arthritis.
A rheumatoid factor (RF) test measures the amount of rheumatoid factor (RF) in your blood. Rheumatoid factors are proteins produced by the immune system. ... An RF test is most often used to help diagnose rheumatoid arthritis.