This type of disease most often affects girls younger than 8 years old. Polyarticular disease is more serious and tends to affect the small joints, such as the hands and feet, and often on both sides of the body. Also called Still's disease, approximately 20 percent of children with juvenile arthritis have this form of the disease. Like adult rheumatoid arthritis, juvenile arthritis is thought to be an autoimmune disease, which means the body's immune system attacks its own healthy cells and tissues. The cause of the disease is unknown.
Researchers believe genetics and environmental factors play a role in the cause of the disease.
The following are the most common symptoms of juvenile arthritis. However each individual may experience symptoms differently. Always consult your physician for a diagnosis. When swelling and inflammation are present, the blood's proteins clump together and become heavier than normal. Thus, when measured, they fall and settle faster at the bottom of the test tube.