Rheumatoid arthritis (RA) can affect many different joints and, in some people, other parts of the body as well, including the blood, the lungs, and the heart.

Inflammation of the joint lining, called the synovium, can cause pain, stiffness, swelling, warmth, and redness. The affected joint may also lose its shape, resulting in loss of normal movement. RA can last a long time and can be a disease of flares (active symptoms) and remissions (few to no symptoms).

RA affects 2.1 million Americans, or about 1% of the adult population in the United States. This disease is 2 to 3 times more common in women than in men, and generally affects people between the ages of 20 and 50. However, young children can develop a form of RA called juvenile rheumatoid arthritis.

What are the symptoms of rheumatoid arthritis?
Symptoms of RA differ from person to person but can generally include:

• Joint tenderness, warmth, and swelling. Both sides of the body are usually affected at the same time. This is also called a "symmetrical pattern" of inflammation. For example, if one knee is affected, the other one is also. This is in contrast to osteoarthritis, where it is possible for only one knee to be affected.
• Pain and stiffness lasting for more than 1 hour in the morning or after a long rest.
• Joint inflammation in the wrist and finger joints closest to the hand (although joints of the neck, shoulders, elbows, hips, knees, ankles, and feet can be affected as well).
• Fatigue, an occasional fever, and a general sense of not feeling well (called malaise).
• Symptoms that last for an extended period of time.
• Symptoms in other parts of the body, not just in the joints.

RA causes inflammation of the joint lining, which can lead to pain, swelling, stiffness, and loss of function. It also can cause inflammation of your tear glands, salivary glands, the lining of your heart and lungs, and the lungs themselves.

As RA progresses, about 25% of people with the disease develop small lumps of tissue under the skin, called rheumatoid nodules. These rheumatoid nodules usually aren't painful. The nodules may form under the skin of the elbow, hands, the back of the scalp, over the knee, or on the feet and heels. They can be as small as a pea to as large as a walnut.

Although RA is often a chronic disease, the severity and duration of the symptoms may unpredictably come and go. For people with a severe case of RA, the disease is generally active, lasts for many years, and leads to serious joint damage and disability. Periods of increased disease activity, or worsening of symptoms, are called flare-ups or flares. Periods of remission are when the symptoms fade or disappear.

If you are experiencing any of the symptoms described above, it is important to find out from a doctor if you have RA. Early diagnosis may reduce the pain, joint damage, and disability that occurs in some RA patients.

What causes rheumatoid arthritis?
RA is an autoimmune disease. This means the body's natural immune system does not operate as it should; it attacks healthy joint tissue, initiating a process of inflammation and joint damage.

The exact cause of RA is not yet known. Although scientists do know that many factors may contribute to the development of RA. Genetic, or hereditary, factors play a role. Scientists have shown certain genes that play a role in the immune system may be involved in determining whether or not you develop RA. However, some people with RA do not have these particular genes, and other people who do have the genes never develop the disease.

Environmental factors may also contribute to the cause of the disease. Researchers have found that RA can be triggered by an infection, possibly a virus or bacterium, in people who have an inherited tendency for the disease. However, RA is not contagious; you can't "catch it" from anyone.

How is rheumatoid arthritis diagnosed?
If you have persistent discomfort and swelling in multiple joints on both sides of your body, make an appointment to see your doctor. Early intervention can ensure that you receive the right diagnosis and help you to start feeling better, sooner. Early intervention can also help prevent irreversible joint damage.

To determine if your symptoms are due to RA, your doctor will most likely:

• Review your medical history and conduct a physical examination.
• Request a blood test that looks for an antibody called rheumatoid factor. About 70% to 90% of people with RA have this antibody. However, it is also possible to have the rheumatoid factor in your blood and not have RA.
• Perform a blood test that measures your erythrocyte sedimentation rate (or sed rate), which will indicate the presence of an inflammatory process in your body. People with RA tend to have abnormally high sed rates.
• Take X-rays of your joints to determine the extent of damage in your affected joints. A sequence of X-rays obtained over time can show the progression of RA.

If you have joint pain, stiffness, and/or swelling for more than 2 weeks, you may have arthritis. Talk with your doctor about your symptoms.