Rheumatoid Arthritis
What causes it?
The exact cause of rheumatoid arthritis (RA) currently is unknown. In fact, there probably isn’t an exact cause for RA. Researchers now are debating whether RA is one disease or several different diseases with common features.
Immune System
We do know that the body’s immune system plays an important role in rheumatoid arthritis. In fact, RA is referred to as an autoimmune disease because people with RA have an abnormal immune system response.
In a healthy immune system, white blood cells produce antibodies that protect the body against foreign substances. People who have RA have an immune system that mistakes the body’s healthy tissue for a foreign invader and attacks it.
One example of this miscommunication in the body is known as rheumatoid factor. Rheumatoid factor is an antibody that is directed to regulate normal antibodies made by the body. It works well in people with small quantities of rheumatoid factor. People with high levels of rheumatoid factor, however, may have a malfunctioning immune system. This is why your doctor often will request a test measuring rheumatoid factor when trying to diagnose RA. In general, the higher the level of rheumatoid factor present in the body, the more severe the disease activity is.
It is important to note that not all people with RA have an elevated rheumatoid factor and not all people with an elevated rheumatoid factor have RA. The test also can come out negative if it is done too early in the course of the disease. Approximately 20 percent of people with RA will have a negative rheumatoid factor test and some people who don’t have RA will test positive.
Learn more about the immune system.
Gender
Women get rheumatoid arthritis two to three times more often then men and their RA typically goes into remission when they get pregnant. Women develop RA more often than expected in the year after pregnancy and symptoms can increase after a baby is born. These facts lead researchers to believe that gender might play a role in the development and progression of RA. Many are trying to understand the effects female hormones might have in the development of RA. Currently, there are limited answers to these questions. For more information on pregnancy and arthritis, see Pregnancy Prognoisis.
Genetics
Most researchers believe there are genes involved in the cause of RA. The specific genetic marker associated with RA, HLA-DR4, is found in more than two-thirds of Caucasians with RA while it is only found in 20 percent of the general population. While people with this marker have an increased risk of developing RA, it is not a diagnostic tool. Many people who have the marker either don’t have or will never get RA. While this marker can be passed from parent to child, it is not definite that if you have RA, your child will too. Learn more about genetics and RA.
Infection
Some physicians and scientists believe that RA is triggered by a kind of infection. There is currently no proof of this. Rheumatoid arthritis is not contagious, although it is possible that a germ to which almost everyone is exposed may cause an abnormal reaction from the immune system in people who already carry a susceptibility for RA.
