What is Rheumatoid Arthritis?

10 Basic Facts about Rheumatoid Arthritis

The HealthCentral Editorial Team Nov 29th, 2012 (updated Aug 4th, 2016)
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RA affects 1.3 million Americans
RA affects 1.3 million Americans

According to the Arthritis Foundation, rheumatoid arthritis (RA) affects about 1.3 million Americans.

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Onset usually occurs between 30 and 50
Onset usually occurs between 30 and 50

But rheumatoid arthritis can occur at any age, from childhood to old age.

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Juvenile idiopathic arthritis is the term for arthritis in children
Juvenile idiopathic arthritis is the term for arthritis in children

 Patients who experience arthritis in only a few joints do better than those with more widespread (systemic) disease, which is very difficult to treat.

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Gender is a factor
Gender is a factor

Women are more likely to develop RA than men.

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The exact cause of RA is unknown
The exact cause of RA is unknown

Rheumatoid arthritis is most likely triggered by a combination of factors, including an abnormal autoimmune response, genetic susceptibility, and some environmental or biologic trigger, such as a viral infection or hormonal changes.

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Rheumatoid arthritis is an autoimmune disease
Rheumatoid arthritis is an autoimmune disease

In autoimmune disorders, the body’s immune system mistakenly attacks and destroys healthy cells and tissue.

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The immune system plays a role in RA inflammation
The immune system plays a role in RA inflammation

For reasons that are still not completely understood, both the T cells and the B cells become overactive in patients with RA.

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Morning stiffness is a hallmark symptom
Morning stiffness is a hallmark symptom

Morning stiffness that lasts for at least an hour is associated with RA. Stiffness from osteoarthritis, in contrast, usually clears up within half an hour.

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Joint swelling and pain also are classic symptoms
Joint swelling and pain also are classic symptoms

Swelling and pain in the joints must occur for at least 6 weeks before a diagnosis of rheumatoid arthritis is considered. The inflamed joints are usually swollen and often feel warm and "boggy" (spongy) when touched. The pain often occurs on both sides of the body (symmetrically) but may be more severe on one side of the body, depending on which hand the person uses more often.

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Nodules can occur
Nodules can occur

In some patients with RA, inflammation of small blood vessels can cause nodules, or lumps, under the skin. They are about the size of a pea or slightly larger, and are often located near the elbow, although they can show up anywhere.