The self-destructive immune response of rheumatoid arthritis may be caused by a combination of genetic susceptibility and an environmental trigger. Changing hormones also may play an important part in the disease, possibly in response to an infection from the environment.

More than one gene has been linked to risk for rheumatoid arthritis. Specific genes may increase a person's chance of developing the disease, and also could partially determine how serious his or her condition is. However, since not all people with a genetic predisposition to rheumatoid arthritis actually have the disease, other factors must be important.

A specific environmental trigger has not yet been found, but some research suggests that infection by a virus or bacterium leads to rheumatoid arthritis in genetically susceptible people. This does not mean that rheumatoid arthritis is contagious. People with rheumatoid arthritis appear to have more antibodies in the synovial fluid in their joints, suggesting that there may be an infection.

Low levels of hormones from the adrenal gland are common in people with rheumatoid arthritis, but how hormones interact with environmental and genetic factors is unknown. Hormone changes may contribute to the progression of the rheumatoid arthritis.

Conditions That Can Cause Rheumatoid Arthritis
Rheumatoid arthritis can occur independently from other conditions, but its causes and relationship to other diseases are not well understood. A different form of chronic arthritis can sometimes develop into rheumatoid arthritis. It also is possible that infections or other environmental triggers exist that can cause rheumatoid arthritis in people that already have a gene for the disease.

Diagnosing Rheumatoid Arthritis
It often is difficult to rule out alternate causes of joint pain during the early stages of rheumatoid arthritis. A diagnosis is based on the symptoms you describe, your medical history, and a physical examination. An x ray, a blood test for rheumatoid factor, and other laboratory tests also may help your doctor to distinguish between other conditions and rheumatoid arthritis.

When to See a Doctor
As we get older, many of us will feel occasional joint pain or discomfort that comes and goes. This does not usually require professional treatment. But you should see a doctor if:
- you regularly have morning stiffness in your joints
- you experience persistent joint pain that does not improve with self-care
- the joint pain is increasing
- the joint is swollen, red, hot, or tender to the touch
- it is difficult to move without pain
- you also have a fever
- several joints on the left and right sides of your body are affected

What to Expect During the Exam
There are many sources of joint pain, and in early rheumatoid arthritis it is often difficult to rule out other causes of your symptoms. Your doctor will try to determine the causes of your symptoms based on your description, your medical history, and a physical examination. They also may use x rays and laboratory tests to distinguish between other conditions and rheumatoid arthritis.

A blood test can be done for rheumatoid factor, which is present in 80% of people with rheumatoid arthritis, but it may not be visible early on. In addition, not everyone with rheumatoid factor has arthritis.

The initial exam is also important in monitoring changes in your health over time. If rheumatoid arthritis is diagnosed, regular doctor visits will allow you to adjust treatments as needed.