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Rheumatoid Arthritis (cont.)

Osteoarthritis vs. Rheumatoid Arthritis

Osteoarthritis is the most common type of arthritis, affecting about 27 million people in the United States. Osteoarthritis is caused by degeneration of cartilage, and is also known as degenerative arthritis. In contrast, rheumatoid arthritis is caused by the immune system attacking the joints. This autoimmune process causes systemic inflammation, while in osteoarthritis, mechanical degeneration causes localized inflammation.

Osteoarthritis commonly affects a single joint, such as one knee. Trauma, such as multiple injuries playing sports, is a risk factor for osteoarthritis. On the other hand, rheumatoid arthritis usually affects three or more joints, in a symmetric distribution (both wrists, both ankles, and/or the toes on both feet). Rheumatoid arthritis frequently, but not always, causes elevation in blood levels of substances that are markers of systemic inflammation such as the ESR (sed rate or erythrocyte sedimentation rate) and CRP (C-reactive protein). In contrast, osteoarthritis does not cause abnormal blood test results. Both osteoarthritis and rheumatoid arthritis are hereditary. For example, if a woman (or man) has osteoarthritis or rheumatoid arthritis, her/his children are at increased risk of developing the same type of arthritis.

What Are the Different Types of Rheumatoid Arthritis?

Symptoms of rheumatoid arthritis usually begin gradually in several joints. Sometimes the symptoms begin only in one joint, and sometimes the symptoms begin initially in the whole body, with generalized stiffness and aching, and then localize to the joints.

  • Typical "classic" rheumatoid arthritis is the most common type of rheumatoid arthritis. Classic rheumatoid arthritis involves three or more joints. Usually, people have a gradual onset of joint pain, stiffness, and joint swelling, usually in the fingers, wrists, and forefeet. Elbows, shoulders, hips, ankles and knees are also commonly affected.
    • About 80% of people with rheumatoid arthritis are classified as "seropositive," which simply means the rheumatoid factor (RF) blood test is abnormal. Some people with an abnormal rheumatoid factor also have an abnormal anti-CCP (anti-citrulline antibody) blood test. This is another blood test for rheumatoid arthritis.
    • Approximately 20% of people with rheumatoid arthritis are classified as "seronegative," which means the rheumatoid factor blood test is negative, or normal. In this case, the anti-CCP blood test may be abnormal or normal. Other blood tests, such as the ESR (sed rate) measure of inflammation, may be abnormal.

Palindromic rheumatism

  • Uncommonly, the onset of rheumatoid arthritis is episodic. One or several joints may be swollen and painful for several hours to several days. The inflammation then subsides for days to months, and then occurs again. This is known as palindromic rheumatism. People with this condition often develop typical "classical" rheumatoid arthritis.

Atypical presentations of RA

  • Persistent arthritis of just one joint may be the first symptoms of rheumatoid arthritis in some people.
  • Some people experience generalized aching, stiffness, weight loss, and fatigue as their initial symptoms of rheumatoid arthritis.
Medically Reviewed by a Doctor on 4/21/2016

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Read What Your Physician is Reading on Medscape

Rheumatoid Arthritis »

Rheumatoid arthritis (RA) is a chronic systemic inflammatory disease of unknown cause that primarily affects the peripheral joints in a symmetric pattern.

Read More on Medscape Reference »


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