What is the definition or description of: rheumatoid factor?

RF assoc. with RA : Rheumatoid factor (rf) is a test that is often sent to evaluate a person with joint pain and stiffness . A positive rf has to be interpreted in the context of the patients symptoms. Sometimes the + rf is false, and not clinically related to the patients symptoms. Rf can be +ve in other conditions such as infections and certain cancers. Some patients with rheumatoid arthritis have a negative rf.

Test for autoimmune: An "rf" is a blood test used to screen a person for the possibility of several autoimmune diseases, including rheumatoid arthritis. It is important to remember that this is a screening test. A positive result only indicates more testing may be warranted, and a negative result does not rule out ra.