At a Glance
Why Get Tested?
When to Get Tested?
When your doctor thinks that you have symptoms suggestive of RA or Sjögren’s syndrome
A blood sample taken from a vein in your arm
The Test Sample
What is being tested?
This test detects and measures rheumatoid factor (RF), a type of “autoantibody”, in the blood. We all have antibodies (also known as immunoglobulins) in our blood, which are protective proteins which defend the body against infection, particularly from bacteria. However, “autoantibodies” may attack the patient’s own tissues mistakenly identifying them as “foreign”. While the role of RF is not well understood, it may not directly cause joint damage, but promote the body's inflammation reaction which in turn contributes to autoimmune joint destruction.
The RF test is sensitive but not very specific, implying it can be found in diseases other than rheumatoid arthritis (RA). It is most closely associated with RA but may also be present in other autoimmune disorders, such as Sjögren’s syndrome, in some persistent bacterial and viral infections, and can be found in a small percentage of healthy people particularly in the elderly.
How is the sample collected for testing?
A blood sample is collected from a vein in your arm.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Ask a Laboratory Scientist
NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.