What is it?
Juvenile Rheumatoid Arthritis (JRA), also sometimes called Juvenile Idiopathic Arthritis (JIA), is the most common type of
arthritis in those under the age of 16, affecting about 50,000 children in the United States. JRA is a chronic condition that causes joint inflammation, pain, swelling, redness, and stiffness. It may also affect the eyes and internal organs. About one-fifth of those with JRA have an enlarged spleen as well as joint inflammation.
JRA is classified into three major types based on the number of joints affected and whether or not the internal organs are involved. These types are:
- Pauciarticular – about 50% of the cases of JRA are of this type. It affects four or less joints and is most common in girls less than 8 years old.
- Polyarticular – about 30% of those with JRA have this type. It affects five or more joints, especially those in the hands and feet, but also other larger joints.
- Systemic – about 20% of those with JRA are of this type. It affects both joints and internal organs. Children with this type may have frequent fevers and rashes that can come and go rapidly.
Each patient’s symptoms will differ and will frequently change over time, with flare-ups and remissions. In a few children, the symptoms may persist; in a few others they may permanently disappear. Doctors consider the diagnosis of JRA in patients who have had symptoms for at least 6 weeks. These symptoms may include morning stiffness, limping, reluctance to move an affected joint, joint pain and swelling. Patients with systemic JRA may have intermittent fever, rash, swollen lymph nodes, and in some cases liver, spleen, and (very rarely) lung involvement. Complications of JRA may include eye inflammation and problems related to joint growth. The disease may cause the affected joints to grow either too quickly or too slowly, causing one arm or leg to be shorter or longer than the other. It may also cause uneven growth in the joint itself. General growth may also be affected by JRA.
The cause of JRA is unknown, but it is thought to be an autoimmune disorder. The tendency to develop it may be inherited, but it is believed that a triggering event is required for it to emerge. It usually begins between the ages of 2 and 5 years or between 9 and 12 years. More girls than boys develop JRA.
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