Juvenile rheumatoid arthritis (JRA), also called juvenile idiopathic arthritis (JIA) and juvenile chronic arthritis (JCA), is the most common childhood arthritis. This disease may affect up to 294,000 children in North America alone.
Juvenile rheumatoid arthritis consists of joint inflammation and stiffness for more than six weeks in a child aged 16 or younger. Inflammation causes redness, swelling, warmth, and soreness in the joints. Still, many children with JRA do not complain of joint pain.
Any joint can be affected with JRA. The ongoing inflammation may limit the mobility of affected joints.
What Causes Juvenile Rheumatoid Arthritis?
JRA is an autoimmune disorder. This means that the body mistakenly identifies some of its own cells and tissues as foreign. Normally, the immune system fights off harmful, foreign substances such as bacteria or viruses. With JRA, the immune system attacks healthy cells and tissues. The result is inflammation -- marked by redness, heat, pain, and swelling.
Researchers don't know exactly why the immune system goes awry in children with JRA. They suspect that it's a two-step process. First, something in a child's genetic makeup gives them a tendency to develop JRA. Then an environmental factor, such as a virus, triggers the development of JRA.
How Is Juvenile Rheumatoid Arthritis Different from Adult RA?
The main difference between juvenile and adult rheumatoid arthritis is that some people with JRA outgrow the illness. Adults with RA usually have lifelong symptoms. Studies show that by adulthood, JRA symptoms disappear in more than half of all affected children. Another difference between JRA and adult rheumatoid arthritis is the percentage of people who have rheumatoid factor in their blood. The presence of rheumatoid factor indicates an increased chance that JRA will continue into adulthood. About 70% to 80% of adults with rheumatoid arthritis have rheumatoid factor. However, fewer than half of all children with rheumatoid arthritis have rheumatoid factor.
What Are the Symptoms of Juvenile Rheumatoid Arthritis?
Besides joint pain, JRA may cause chronic fever and anemia. It can affect the heart, lungs, eyes, and nervous system.
These episodes may last for several weeks. The arthritis flares often recur, but the symptoms may be less severe in recurrent attacks. Symptoms of JRA may include:
Are There Different Types of Juvenile Rheumatoid Arthritis?
Doctors classify three kinds of JRA. Each type is based on the number of joints involved, the symptoms, and the presence of certain antibodies in the blood. These three different classifications help determine how the disease will progress.