Juvenile arthritis is a disease in which there is inflammation (swelling) of the synovium in children aged 16 or younger. The synovium is the tissue that lines the inside of joints.
Juvenile arthritis is an autoimmune disease. That means the immune system, which normally protects the body from foreign substances, attacks the body instead. The disease is also idiopathic, which means that no exact cause is known. Researchers believe juvenile arthritis may be related to genetics, certain infections, and environmental triggers.
Rheumatic diseases are painful conditions usually caused by inflammation, swelling, and pain in the joints or muscles.
Some rheumatic diseases like osteoarthritis are the result of "wear and tear" to the joints. Other rheumatic diseases, such as rheumatoid arthritis, happen when the immune system becomes hyperactive; the immune system attacks the linings of joints, causing joint pain, swelling, and destruction.
Almost any joint can be affected in rheumatic disease. There are more than 100 rheumatic...
Because a child may have no symptoms of juvenile arthritis, and because some of the symptoms can be associated with other diseases, a diagnosis may be difficult. Because there is no actual test for juvenile arthritis, the diagnosis is made by excluding other conditions that may cause similar symptoms, such as bone disorders or breaks, fibromyalgia, infection, Lyme disease, lupus, or cancer.
The doctor is likely to begin by taking a complete medical history and performing a complete medical exam. Additional testing might be useful in determining what type of arthritis the child has. Some of the other tests that might be ordered include:
Bone marrow exam, which is used to check for leukemia
Erythrocyte sedimentation rate to see how quickly the red blood cells fall to the bottom of a test tube (The rate is faster in most people who have a disease that causes inflammation.)
Test for rheumatoid factor, an antibody that may be found in people with arthritis (An abnormal result is more common in adults than in children.)
Antinuclear antibody test to show evidence of autoimmunity (Autoimmunity is a disease state in which the body's defense system, the immune system, malfunctions and attacks the body itself. This test is also useful in predicting if eye disease will develop in children with juvenile arthritis.)
Bone scan to detect changes in bones and joints (This test may be ordered if the symptoms include unexplained pain in the joints and bone.)
Joint fluid sampling and synovial tissue sampling, which might be performed by an orthopedic surgeon