According to the Arthritis Foundation, rheumatoid arthritis affects about 1.3 million people in the United States. It is a life-long disease in which there is inflammation of the synovial membrane, which is the part of the joint that secretes synovial fluid. It affects the small joints of the fingers, wrists and hands. Symptoms include weakness, swollen joints, pain and stiff joints. The cause of rheumatoid arthritis is unknown, but there are several theories as to why it occurs.
Autoimmune Reaction
Normally, the immune system is supposed to protect the body from disease-causing agents. It does this by identifying and destroying any foreign object that could cause disease. In an abnormal autoimmune reaction, the immune system attacks and destroys healthy parts of the body. The Merck Manuals Online Medical Library suggests that rheumatoid arthritis is an autoimmune disease that happens when the body's immune system attacks the soft tissue, known as the synovial membrane, that lines the joints.
Infection
The Cleveland Clinic notes that a possible cause of rheumatoid arthritis is infection. It is known that some infections such as strep throat trigger an autoimmune reaction in the body that leads to the development of rheumatic fever or kidney disease. Though scientific evidence for this is lacking, the Arthritis Foundation suggests that people who are susceptible to rheumatoid arthritis may develop it when exposed to certain infectious agents.
Genetics
Genetics may a play a role in the development of rheumatoid arthritis. According to "Johns Hopkins White Papers, 2007, Arthritis," rheumatoid arthritis may run in certain families without conferring risk for the disease on members of those families. However, there is a genetic marker that is seen in more than two-thirds of white men and women who have rheumatoid arthritis. At the same time, 1 in 5 people who do not have rheumatoid arthritis also have this marker. So while this genetic marker may indicate a risk for rheumatoid arthritis, it doesn't mean that people who have it will develop arthritis.
References
- Merck Manuals Online Medical Library: Rheumatoid Arthritis (RA)
- Arthritis Foundation: Reumatoid Arthritis- What Caues It?
- "The Cleveland Clinic Guide to Arthritis"; John Clough; 2009
- "Johns Hopkins White Papers, 2007, Arthritis"; John A. Flynn, M.D., Timothy Johnson; 2007
- Medline Plus: Strep Throat
