Learn how a rheumatoid arthritis diagnosis can be difficult to achieve.
Rheumatoid arthritis is an autoimmune disease that develops when the body's immune system malfunctions, attacking the healthy cells of the joints and causing pain and joint damage. Rheumatoid arthritis is difficult to diagnose, as there is no single definitive test to indicate the presence of the disease. A doctor must rely on an evaluation of several factors to diagnose rheumatoid arthritis. According to the American College of Rheumatology, there are seven criteria used to diagnose and classify the severity of rheumatoid arthritis. These criteria include both a physical examination of the patient and interpretation of laboratory tests and X-rays.
Early symptoms can be subtle and often mimic the symptoms of other joint diseases, complicating the diagnosis. No two patients present exactly the same symptoms; however, the presence of certain hallmark symptoms can clarify the diagnosis. Morning stiffness lasting longer than 30 minutes is characteristic of rheumatoid arthritis. Pain is often symmetrical, with the hands, wrists and balls of the feet most commonly affected, although any joint in the body may be involved. Fatigue and flu-like symptoms may also be present. Upon examination, the physician looks for redness, warmth and swelling of the joints. Nodules, due to inflammation of small blood vessels under the skin, are present in about 20 percent of patients with rheumatoid arthritis. During the physical examination, the doctor will also test reflexes and muscle strength.
Blood tests are useful in establishing the diagnosis of rheumatoid arthritis. Several common laboratory tests can provide useful diagnostic information. As anemia is a common complication of rheumatoid arthritis, a red blood cell count is taken. An elevated level of C-reactive protein (CRP) and a high erythrocyte sedimentation rate (ESR) are laboratory indicators of inflammation and disease activity in the body. It is also possible to measure, with a blood test, the presence of two antibodies that are commonly found in rheumatoid arthritis patients.
An antibody is a necessary part of the immune system's fight against foreign substances in the body. The presence of anti-cyclic citrullinated peptide (CCP) antibodies can help to identify rheumatoid arthritis even before symptoms develop. According to the Johns Hopkins University Arthritis Center, the anti-CCP diagnostic test is more accurate and more specific than RF in diagnosing early rheumatoid arthritis. Although helpful, these tests are not definitive. According to the Mayo Clinic, it is possible for rheumatoid factor to be present in healthy people. Likewise, some people who have rheumatoid arthritis test negative for rheumatoid factor. Rheumatoid factor may also be present in people who have chronic infections or other autoimmune diseases, but not rheumatoid arthritis.
Most imaging techniques are used to track the progression of the disease after diagnosis, as well as for the initial diagnosis. Joint damage is not visible by X-ray for 3 to 6 months following the onset of the disease. X-rays may be useful in diagnosing rheumatoid arthritis in its later stages, after joint damage has occurred.
Ultrasound techniques are used to monitor both bone loss in the fingers, an indicator of early stage rheumatoid arthritis, and inflammatory activity in the joints. Magnetic resonance imaging (MRI) technology is currently being evaluated for its ability to detect bone erosions in the hands of rheumatoid arthritis patients.