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    What Is Rheumatoid Arthritis?

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    Arthritis means inflammation in a joint. That inflammation causes redness, warmth, swelling, and pain within the joint.

    Rheumatoid arthritis affects joints on both sides of the body, such as both hands, both wrists, or both knees. This symmetry helps to set it apart from other types of arthritis.

    RA can also affect the skin, eyes, lungs, heart, blood, or nerves.

    What Are the Symptoms?

    The warning signs of RA are:

    • Joint pain and swelling
    • Stiffness, especially in the morning or after you sit for a long time
    • Fatigue

    Rheumatoid arthritis affects everyone differently. For some, joint symptoms develop gradually over several years. In others, it may come on quickly.

    Some people may have rheumatoid arthritis for a short time and then go into remission, which means they don’t have symptoms.

    Who Gets Rheumatoid Arthritis?

    Anyone can get RA. It affects about 1% of Americans.

    The disease is two to three times more common in women than in men, but men tend to have more severe symptoms.

    It usually starts in middle age. But young children and the elderly also can get it.

    What Causes It?

    Doctors don’t know the exact cause. Something seems to trigger the immune system to attack the joints and sometimes other organs. Some experts think that a virus or bacteria may change the immune system, causing it to attack the joints. Other theories suggest that in some people, smoking may lead to rheumatoid arthritis.

    Certain genetic patterns may make some people more likely to get RA than others.

    How Does It Affect the Body?

    Immune system cells move from the blood into the joints and joint-lining tissue, called synovium. Once they arrive, those immune system cells create inflammation that leads to irritation, which wears down cartilage (the cushioning material at the end of bones). As the cartilage wears down, the space between the bones narrows. As it gets worse, the bones could rub against each other.

    Inflammation of the joint lining causes swelling and makes fluid build up within the joint. As the lining expands, it can damage the bone.

    All of these things cause the joint to become very painful, swollen, and warm to the touch.

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