A rheumatoid arthritis factor test is a simple blood test that takes only a few minutes to complete, according to Healthline. The test is performed by drawing a blood sample from a vein in the arm or back of the hand.
A rheumatoid arthritis factor test measures the amount of the rheumatoid factor, or RF, antibody in the blood, notes Lab Tests Online. It helps diagnose rheumatoid arthritis and definitively distinguish it from other types of arthritis. Under normal conditions, the immune system produces antibodies that eliminate bacteria and viruses causing disease, explains WebMD. Rheumatoid arthritis occurs when the RF antibody attacks normal tissue, causing pain, inflammation and erosion in the joints, including the hands, wrists, neck and hips.