Rheumatoid Factor Testing (RF)

Rheumatoid factor (RF) is a protein naturally present in your blood. It is made by your immune system, but can mistakenly identify your own tissue as "foreign" and cause an attack on your own body.

80% of people with rheumatoid arthritis will have elevated RF levels. So rheumatoid factor (RF) testing is a useful tool to help identify the presence of this autoimmune condition. However, it is important to note that rarely, patients without rheumatoid arthritis may have an elevated level of RF and patients may have rheumatoid arthritis but do not have an elevated RF