Rheumatoid arthritis is the most common inflammatory form of arthritis. It is considered an autoimmune disease- a disease where the immune system attacks the joints. This article discusses how a rheumatologist makes the diagnosis early on.
The cause of the immune abnormality that occurs in rheumatoid arthritis still has no definite explanation. Some suspect an environmental trigger such as a virus or bacterium interacts with specific genes that a patient may have. This leads to a cascade of events culminating in inflammation. The immune attack occurs at the site of the synovium- the lining of the joints. White blood cells flood this area and release destructive enzymes. This sequence of events leads to inflammation of the synovium, erosion of cartilage and bone, and subsequent weakening of tendons, ligaments, and muscles. Because it is a systemic illness, rheumatoid arthritis may affect other organ systems in the body such as the eyes and heart.
Early diagnosis is not always easy. The joint swelling that is characteristic of rheumatoid arthritis may not be that pronounced. Sometimes fatigue, low-grade fever, weight loss, loss of appetite, and stiffness, may be the chief symptoms- but these symptoms can occur with other diseases as well!
Over a period of a few weeks to months, joint symptoms such as pain, redness, and swelling can develop and be accompanied by loss of function.
Morning stiffness is a key component of rheumatoid arthritis. This generally lasts more than an hour. Patients may also complain of stiffness during the day if they sit for any length of time.
Examination may reveal swelling affecting multiple joints , both small and large- although small joints of the hands, wrists, ankles, and feet are moist commonly involved.
Bumps under the skin near joints such as the fingers and elbows may occur. These are called rheumatoid nodules.
Laboratory tests are helpful. Elevation of erythrocyte sedimentation rate (ESR) or C-reactive protein indicate systemic inflammation. A positive rheumatoid factor is seen in about 80-85% of patients. The rheumatoid factor may be negative early on and may be persistently negative in 20% of patients. Anti-CCP- a new diagnostic test – is more specific for rheumatoid arthritis than the rheumatoid factor, which may be positive in other conditions.
Magnetic resonance imaging (MRI) and diagnostic ultrasound are helpful imaging tests for early diagnosis. X-rays may not become positive until a patient has had their disease for at least six months and are therefore not useful for early diagnosis.
