Arthritis that develops in children younger than 16 years is known as juvenile arthritis (JA). Approximately one in every 500 children develops some form of JA. It is unclear exactly what causes JA, though it is thought to be a combination of genetic and environmental factors.
About 300,000 Americans have JA, and about 25 percent of those have polyarticular JA, which is characterized by an inflammation in five or more joints. Polyarticular JA is predominately seen in finger and hand joints, but it also can occur in weight-bearing joints such as the knees, and joints surrounding the jaw bone.
How does polyarticular juvenile arthritis affect the body?
Polyarticular JA is separated into two categories, distinguished by the presence or absence of rheumatoid factors. Rheumatoid factors are proteins produced by the immune system that can damage healthy tissues that make up body joints.
Rheumatoid factor-positive polyarticular JA resembles adult rheumatoid arthritis and usually is the most severe of the two forms of polyarticular JA. Symptoms may include severe inflammation, anemia, considerable fatigue, reduced appetite and weight loss, and general feelings of illness, including persistent low-grade fevers. Rheumatoid nodules, which are hard lumps that develop under the skin, also are indicators of rheumatoid factor-positive polyarticular JA.
Rheumatoid factor-negative polyarticular JA, is more prevalent than rheumatoid factor-positive JA, occurring in approximately 20 percent of children with JA, and it is more likely to persist into adulthood. Patients may exhibit joint inflammation and growth issues.
How is polyarticular juvenile arthritis diagnosed?
Polyarticular JA is diagnosed based on the physical symptoms of the patient and blood concentration of rheumatoid factors. Physical symptoms may be examined further with X-rays of the affected joints. A high level of anti-CCP antibodies, which is typically known as a pre-indicator for rheumatoid arthritis in adults, also is frequently seen in children with polyarticular JA and in many cases correlates with disease severity.
How is polyarticular JA treated?
There is no cure for polyarticular JA, but there are multiple therapies that can be used to reduce symptoms and improve the quality of life of patients. As with most forms of arthritis, physicians may prescribe steroids or non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, to limit pain and inflammation. The progress of arthritis can be slowed or stopped with the use of disease-modifying anti-rheumatic drugs (DMARDs).
Though these drugs typically improve symptoms for most arthritis patients, they are slightly less effective in children with polyarticular JA. Physicians also may prescribe biologic agents, such as antibodies, interleukins, or proteins, which are increasingly becoming recognized as potential therapies for the disease.
Research is ongoing to develop potential new drugs to treat different forms of JA.
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