Rheumatoid Arthritis Health Article

Definition

Rheumatoid arthritis (RA) is a chronic disease causing inflammation and deformity of the joints. Other systemic problems throughout the body may also develop, including inflammation of blood vessels (vasculitis), the development of bumps (rheumatoid nodules) in various parts of the body, lung disease, blood disorders, and weakening of the bones (osteoporosis).

Description

The skeletal system of the body is made up of different types of strong, fibrous tissue called connective tissue. Bone, cartilage, ligaments, and tendons are all forms

of connective tissue that have different compositions and characteristics.

The joints are structures that hold two or more bones together. Synovial joints allow for movement between the bones being joined, the articulating bones. The simplest synovial joint involves two bones, separated by a slight gap called the joint cavity. The ends of each articular bone are covered by a layer of cartilage. Both articular bones and the joint cavity are surrounded by a tough tissue called the articular capsule. The articular capsule has two components: the fibrous membrane on the outside and the synovial membrane, or synovium, on the inside. The fibrous membrane may include tough bands of tissue called ligaments, which are responsible for providing support to the joints. The synovial membrane has special cells and many tiny blood vessels called capillaries. This membrane produces a supply of synovial fluid that fills the joint cavity, lubricates it, and helps the articular bones move smoothly about the joint.

In rheumatoid arthritis, the synovial membrane becomes severely inflamed. Usually thin and delicate, the synovium becomes thick and stiff, with numerous infoldings on its surface. The membrane is invaded by white blood cells, which produce a variety of destructive chemicals. The cartilage along the articular surfaces of the bones may be attacked and destroyed, and the bone, articular capsule, and ligaments may begin to erode. These processes severely interfere with movement in the joint.

RA exists all over the world and affects men and women of all races. In the United States alone, about two million people suffer from the disease. Women are three times more likely than men to have RA. About 80% of people with RA are diagnosed between the ages of 35 and 50. RA appears to run in families, although certain factors in the environment may also influence the development of the disease.

Causes & symptoms

The underlying event that promotes RA in a person is unknown. Given the known genetic factors involved in RA, some researchers have suggested that an outside event occurs and triggers the disease cycle in a person with a particular genetic makeup. In late 2001, researchers announced discovery of the genetic markers that predict increased risk of RA. The discovery should soon aid research into diagnosis and treatment of the disease. Recent research has also shown that several autoimmune diseases, including RA, share a common genetic link. In other words, patients with RA might share common genes with family members who have other autoimmune diseases like systemic lupus, multiple sclerosis, and others.

Many researchers are examining the possibility that exposure to an organism (a bacteria or virus) may be the first event in the development of RA. The body's normal response is to produce cells that can attack and kill the organism, protecting the body from the foreign invader. In an autoimmune disease like RA, this immune cycle spins out of control. The body produces misdirected immune antibodies, which accidentally identify parts of the person's body as foreign. These immune cells then produce a variety of chemicals that injure and destroy parts of the body.

Reports in late 2001 suggest that certain stress hormones released during pregnancy may affect development of RA and other autoimmune diseases in women. Researchers have observed that women with autoimmune disorders will often show lessened symptoms during the third trimester of pregnancy. The symptoms then worsen in the year after pregnancy. Further, women appear to be at higher risk of developing new autoimmune disorders following pregnancy.

RA can begin very gradually or it can strike without warning. The first symptoms are pain, swelling, and stiffness in the joints. The most commonly involved joints include hands, feet, wrists, elbows, and ankles. The joints are typically affected in a symmetrical fashion. This means that if the right wrist is involved, the left wrist is also involved. Patients frequently experience painful joint stiffness when they first get up in the morning, lasting perhaps an hour. Over time, the joints become deformed. The joints may be difficult to straighten, and affected fingers and toes may be permanently bent. The hands and feet may also curve outward in an abnormal way.

Many patients also notice increased fatigue, loss of appetite, weight loss, and sometimes fever. Rheumatoid nodules are bumps that appear under the skin around the joints and on the top of the arms and legs. These nodules can also occur in the tissue covering the outside of the lungs and lining the chest cavity (pleura), and in the tissue covering the brain and spinal cord (meninges). Lung involvement may cause shortness of breath and is seen more in men. Vasculitis, an inflammation of the blood vessels, may interfere with blood circulation. This can result in irritated pits (ulcers) in the skin, gangrene, and interference with nerve functioning that causes numbness and tingling.