Juvenile Idiopathic Arthritis – JIA (once called Juvenile Rheumatoid Arthritis - JRA) is one of the most common autoimmune diseases of childhood and can affect any joint of the body, but most typically the hands, wrists, elbows, shoulders, knees, and ankles. Skin, muscles, blood vessels, eyes, and lungs can also be involved with permanent damage and long-term disability if not aggressively treated. JIA is usually a chronic disease with periods of flares, active disease, and even time periods of quiet disease on medication, and sometimes remission. There is no cure for JIA, but treatment, which, for many patients needs to be lifelong, can slow disease progression and in some halt the inflammation completely. JIA can be particularly devastating when acquired at a young age.
The most common symptom with all types of JIA is joint swelling, pain, and stiffness. These symptoms are typically worse in the morning or after a nap. Many small children, however, will not complain of the pain, but will limp or have decreased activity. The joints most often affected are in the knees, hands, and feet. Beside joint symptoms, children with systemic JRA have a high fever and a pink rash. Also, these children may have swelling of lymph nodes and internal organs. The iris of the eye can also be involved with intense inflammation leading to blindness if not treated properly.
JIA diagnosis is made by a combination of medical history, physical exam, lab tests, and medical imaging (X-rays, bone scan, or MRI). A doctor may take X-rays or blood tests to rule out other diseases that mimic JIA such as Lyme diseases, physical injury, bacterial infection, inflammatory bowel disease, lupus, dermatomyositis, and some forms of cancer. There are no lab tests that can specifically diagnosis JIA – thus it is a diagnosis made after other possible causes for the swollen joints are ruled out.
Erythrocyte sedimentation rate
This test checks how quickly red blood cells settle to the bottom of a test tube. This rate often increases when inflammation is occurring in the body. In JIA this can be elevated or normal.
This is an antibody produced in the blood of children with some forms of JIA (only about 5 percent) but this antibody is more commonly found in adults with RA.
ANA (Antinuclear Antibody)
This is a test performed on the blood to detect autoantibodies against nuclear proteins. It may be positive or negative in children with JIA, but if positive is helpfulin predicting which children are likely to have eye disease with JIA.
JIA by definition occurs before age 16 and occurs throughout childhood in both girls and boys. However, the most frequent form (few joint arthritis) is most common in toddlers. Over all, more girls develop JIA more frequently than boys. Like adult rheumatoid arthritis, many doctors don't know why the immune system goes awry, but researchers suspect that it takes multiple gene abnormalities to create a tendency to develop JIA. These multiple gene abnormalities are not yet identified but may be inherited. It is thought that in a susceptible individual an environmental factor, such as a virus, triggers the onset of JIA.