Genetic (inherited) factors: Scientists have discovered that certain genes known to play a role in the immune system are associated with a tendency to develop rheumatoid arthritis. Some people with rheumatoid arthritis do not have these particular genes; still others have these genes but never develop the disease. These somewhat contradictory data suggest that a person's genetic makeup plays an important role in determining if he or she will develop rheumatoid arthritis, but it is not the only factor. What is clear, however, is that more than one gene is involved in determining whether a person develops rheumatoid arthritis and how severe the disease will become.
Environmental factors: Many scientists think that something must occur to trigger the disease process in people whose genetic makeup makes them susceptible to rheumatoid arthritis. A viral or bacterial infection appears likely, but the exact agent is not yet known. This does not mean that rheumatoid arthritis is contagious: a person cannot catch it from someone else.
Other factors: Some scientists also think that a variety of hormonal factors may be involved. Women are more likely to develop rheumatoid arthritis than men, pregnancy may improve the disease, and the disease may flare after a pregnancy. Breastfeeding may also aggravate the disease. Contraceptive use may alter a person's likelihood of developing rheumatoid arthritis. Scientists think that levels of the immune system molecules interleukin 12 (IL-12) and tumor necrosis factor-alpha (TNF-α) may change along with the changing hormone levels seen in pregnant women. This change may contribute to the swelling and tissue destruction seen in rheumatoid arthritis. These hormones, or possibly deficiencies or changes in certain hormones, may promote the development of rheumatoid arthritis in a genetically susceptible person who has been exposed to a triggering agent from the environment.
Even though all the answers are not known, one thing is certain: rheumatoid arthritis develops as a result of an interaction of many factors. Researchers are trying to understand these factors and how they work together.
Rheumatoid Arthritis Diagnosis
Diagnosing and treating rheumatoid arthritis requires a team effort involving the patient and several types of health care professionals. A person can go to his or her family doctor or internist or to a rheumatologist. A rheumatologist is a doctor who specializes in arthritis and other diseases of the joints, bones, and muscles. As treatment progresses, other professionals often help. These may include nurses, physical or occupational therapists, orthopedic surgeons, psychologists, and social workers.
Rheumatoid arthritis can be difficult to diagnose in its early stages for several reasons. First, there is no single test for the disease. In addition, symptoms differ from person to person and can be more severe in some people than in others. Also, symptoms can be similar to those of other types of arthritis and joint conditions, and it may take some time for other conditions to be ruled out. Finally, the full range of symptoms develops over time, and only a few symptoms may be present in the early stages. As a result, doctors use a variety of the following tools to diagnose the disease and to rule out other conditions:
Medical history: This is the patient's description of symptoms and when and how they began. Good communication between patient and doctor is especially important here. For example, the patient's description of pain, stiffness, and joint function and how these change over time is critical to the doctor's initial assessment of the disease and how it changes over time.
Physical examination: This includes the doctor's examination of the joints, skin, reflexes, and muscle strength.
Laboratory tests: One common test is for rheumatoid factor, an antibody that is present eventually in the blood of most people with rheumatoid arthritis. (An antibody is a special protein made by the immune system that normally helps fight foreign substances in the body.) Not all people with rheumatoid arthritis test positive for rheumatoid factor, however, especially early in the disease. Also, some people test positive for rheumatoid factor, yet never develop the disease. Other common laboratory tests include a white blood cell count, a blood test for anemia, and a test of the erythrocyte sedimentation rate (often called the sed rate), which measures inflammation in the body. C-reactive protein is another common test that measures disease activity.
X rays: X rays are used to determine the degree of joint destruction. They are not useful in the early stages of rheumatoid arthritis before bone damage is evident, but they can be used later to monitor the progression of the disease.