Juvenile rheumatoid arthritis (RA), also known as juvenile idiopathic arthritis or JIA, is a common type of arthritis seen in children ages 16 and younger. The term idiopathic means that the exact cause of the condition is unknown, and medical professionals are unsure why children develop JIA.
Researchers believe that both genetics and environment play a role in developing JIA. For example, a child may be infected with a virus that causes the immune system to attack the joints. They may also inherit a certain gene from their parents known as human leukocyte antigen (HLA)-DR4. A child with this antigen may be more likely to develop JIA.
JIA is an autoimmune disease in which the body’s immune system attacks healthy tissues and joints — specifically, the lining of the joints (known as the synovium). This condition leads to painful, swollen joints that can be difficult to move.
There are six types of JIA, each affecting different areas of the body and displaying different symptoms:
Systemic JIA affects the entire body, including joints, skin, and internal organs. Symptoms include development of a rash and a high spiking fever (103 degrees Fahrenheit) that lasts for at least two weeks.
Oligoarthritis affects four or fewer joints, most often the large joints (elbows, knees, and ankles).
Polyarthritis affects five or more joints, most often on both sides of the body (known as symmetrical arthritis). This can affect both large and small joints (fingers, toes, and wrists).
Enthesitis-related JIA, also known as spondyloarthritis, affects the entheses where muscles, tendons, and ligaments attach to the bone. Affected areas include the feet, knees, hips, elbows, and pelvis.
People with psoriatic arthritis (PsA) can present with both joint and skin psoriasis symptoms, which include a scaly rash. Affected joints can include the knees, ankles, toes, wrists, or fingers.
Undifferentiated JIA includes conditions in which the symptoms do not match up with any other subtype of JIA, but there is inflammation in one or more joints.
The age at which a child develops JIA can depend on the subtype they have. Most cases develop before the age of 16, but some can also develop sooner. For example, enthesitis-related JIA typically develops in children between the ages of 8 and 15.
In the United States, almost 300,000 children under the age of 18 are living with JIA or other rheumatic diseases. Different subtypes are also more common than others. The most common type is oligoarthritis. Polyarthritis affects around 25 percent of children with JIA, and systemic arthritis is seen in 10 percent of these cases.
Similar to adults, children can have both chronic symptoms or flare-ups (episodes of worsened symptoms). Every child will experience JIA symptoms differently. Some common symptoms include:
The tests used to diagnose juvenile cases of RA are the same as those for adults. Blood tests are performed to look for rheumatoid factor (RF), antibodies, and C-reactive protein (CRP) levels. These tests tell a rheumatologist (a doctor that specializes in inflammatory and rheumatic diseases) the levels of inflammation in the body.
Imaging tests may also be performed to look at joint damage and swelling. An X-ray or magnetic resonance imaging (MRI) will tell a rheumatologist how much damage has been done to the bones, cartilage, and soft tissues in joints. These images can help them diagnose JIA and decide what treatment options may be best for the child.
JIA treatments work by targeting the source of inflammation or by treating symptoms. These medications are also used to treat RA in adults. In addition, physical and occupational therapy can help children with JIA manage their condition.
Disease-modifying antirheumatic drugs (DMARDs) help slow the progression of JIA by addressing inflammation at the source. These medications work by broadly inhibiting the immune system, preventing immune cells from damaging healthy joints and tissues. Examples of DMARDs include:
Biologics are a newer type of DMARD used to treat JIA. They contain human-made proteins that dampen the immune system and decrease inflammation throughout the body. There are four different classes of biologics that each target a different part of the immune system. This can include blocking specific immune cells, or chemical messengers that create inflammation. Examples of biologics used to treat JIA include:
Nonsteroidal anti-inflammatory drugs (NSAIDs) are over-the-counter medications often used as pain relievers. However, they can be used to manage JIA symptoms. NSAIDs work by blocking the production of the protein prostaglandin, which is responsible for triggering pain and inflammation. Examples of NSAIDs include:
Steroids (also known as corticosteroids) can also be used to manage acute symptoms of JIA while reducing inflammation and slowing joint damage. Corticosteroids work by mimicking the action of the stress hormone cortisol, which reduces inflammation. Doctors will prescribe corticosteroids, such as prednisone, as a “burst” therapy to help treat pericarditis (inflammation around the heart) or fevers in children with systemic JIA. They can also be used to help manage symptoms while waiting for DMARDs to take full effect.
Physical exercise is an important aspect of being a healthy child. Physical and occupational therapy can help children stay active and learn how to perform daily tasks that might otherwise be difficult. Children with JIA may have difficulties with motor skills and balance, and therapy can help address these issues. They may be given exercises or prescribed assistive devices (such as braces or splints) to help improve mobility and balance.
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