Arthritis: Rheumatoid Arthritis Basics

How Does rheumatoid arthritis Affect the Body?

Once the immune system is triggered, immune cells migrate from the blood into the joints and joint-lining tissue, called synovium. There the immune cells produce inflammatory substances. The increased number of cells and inflammatory substances within the joint cause irritation, wearing down of cartilage (cushioning material at the end of bones), and swelling and inflammation of the joint lining. Inflammation of the joint lining stimulates it to produce excessive joint fluid within the joint.

As the cartilage wears down, the space between the bones narrows. If the condition worsens, the bones could rub against each other.

As the joint lining expands, it may invade into, or erode, the adjacent bone, resulting in irreversible bone damage. All of these factors cause the joint to become very painful, swollen, and warm to the touch.

How Is rheumatoid arthritis Diagnosed?

The diagnosis of rheumatoid arthritis is based on a combination of factors, including:

• The specific location and symmetry of painful joints, especially the hand joints.
• The presence of joint stiffness in the morning.
• Presence of bumps and nodules under the skin (rheumatoid nodules).
• Results of X-ray tests that suggest rheumatoid arthritis.
• Positive results of a blood test called the rheumatoid factor.

Most, but not all, people with rheumatoid arthritis have the rheumatoid-factor antibody in their blood. (Rheumatoid factors are actually antibodies that bind other antibodies.) Rheumatoid factor may sometimes be present in people who do not have rheumatoid arthritis. Other diseases can also cause the rheumatoid factor to be produced in the blood. Therefore, the diagnosis of rheumatoid arthritis is based on a combination of the joint symptoms and appearance as well as laboratory information and not just the presence of the rheumatoid factor in the blood.

A newer, more specific blood test for rheumatoid arthritis is the citrulline antibody test. When positive, it is very suggestive of rheumatoid arthritis. Citrulline antibody presence also implies a tendency toward a more aggressive form of rheumatoid arthritis.

People with rheumatoid arthritis may have a mild anemia. Blood tests may also reveal an elevated erythrocyte sedimentation rate (ESR) or elevated C-reactive protein (CRP) levels, which are markers of inflammation.

Some people with rheumatoid arthritis may also have a positive antinuclear antibody test (ANA). This test is indicative of the fact that rheumatoid arthritis is an autoimmune disease.

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