Test Details: Rheumatoid factor (RF) test determines the presence of rheumatoid antibodies in the body. These are the autoantibodies produced by body's own immune system that attack the healthy tissues of the body. This test is helpful to detect rheumatic diseases like rheumatoid arthritis, diagnose an autoimmune disease like Sjogren's syndrome or Lupus Erythematosus and monitor and treat chronic illnesses.