The Arthritis Foundation defines rheumatoid arthritis (RA) as a chronic disease in which inflammation of the joints (and sometimes other parts of the body) leads to long-term damage that may result in chronic pain, loss of function, and disability.
The Cause of Rheumatoid Arthritis
Despite years of research, RA's cause is unknown as of 2009. Research by the National Institute of Arthritis and Musculoskeletal and Skin Diseases has identified a genetic variation that increases the risk of RA, but researchers have been unable to identify specific genes that cause the disease.
Rheumatoid factors are auto antibodies. Auto antibodies are proteins in the blood created by the body's immune system. These proteins can attack healthy tissue and cause inflammation.
The Rheumatoid Factor Test
The quantity of rheumatoid factors in the body is measurable through a blood test called the rheumatoid factor test. This test, along with other observations, helps physicians make a diagnosis of RA.
Accuracy of the Test
The test can give both false positive and false negative results. The rheumatoid factor can be present if you have lupus, mononucleosis, liver disease or other conditions. The Mayo Clinic reports that the rheumatoid factor also can be detected in healthy people while people with rheumatoid arthritis can have normal levels of rheumatoid factor.
How Results are Reported
The longer a person has RA, the more often the rheumatoid factor will be measurable. Laboratories report results of the test using titers or units. A titer measures dilution levels of the blood sample; a unit measures how much light is blocked by the blood sample. Generally, a rheumatoid factor higher than 23 units or a titer higher than 1:80 indicates the presence of rheumatoid arthritis.