How is rheumatoid arthritis diagnosed?
The diagnosis of rheumatoid arthritis is based on a combination of factors, including:
- Morning stiffness that lasts at least one hour and has been present for at least six weeks;
- Swelling of three or more joints for at least six weeks;
- Swelling of the wrist, hand, or finger joints for at least six weeks;
- Swelling of the same joints on both sides of the body;
- Changes in hand x-rays that are hallmarks of rheumatoid arthritis;
- Rheumatoid nodules (lumps) of the skin
- Blood test that is positive for rheumatoid factor* and/or anti-citrullinated peptide/protein antibodies
* The rheumatoid factor may be present in people who do not have rheumatoid arthritis. Other diseases can also cause the rheumatoid factor to be produced in the blood. A test called CCP antibody can sometimes help to determine whether the rheumatoid factor antibody is due to rheumatoid arthritis or some other disease. This is why the diagnosis of rheumatoid arthritis is based on a combination of several factors and NOT just the presence of the rheumatoid factor in the blood.
It is also important to note that not all of these features are present in people with early rheumatoid arthritis, and these problems may be present in some people with other rheumatic conditions.
In some cases, it may be necessary to monitor the condition over time before a definitive diagnosis of rheumatoid arthritis can be made.