Rheumatoid factors (RF) are autoantibodies directed against an immunoglobulin G. They are found in 75 to 80 percent of Rheumatoid Arthritis (RA) patients at some time during the course of their disease but it also occurs in other diseases.
As an example, some connective tissue diseases, such as systemic lupus erythematosus and primary Sjögren’s syndrome or certain infections, such as malaria, rubella, hepatitis C and, eventually, following some vaccinations. RF may also be present in a significant percentage of healthy population.
The presence of RF in the general population has little predictive value since the overall disease prevalence is relatively low. However, the presence of RF in RA patients is often associated with more aggressive joint disease. High levels of RF may antedate the clinical development of RA but, in absence of any suggestive clinical, analytical or radiological findings, RF DOES NOT, BY ITSELF, INDICATES THE PRESENCE OF RA.
In case you have a positive test for RF is highly recommended to find an expert that balances its clinical significance depending on your symptoms, analytical abnormalities and radiological findings.