Some forms of arthritis can strike children or even infants. By far, the most common type of childhood arthritis is juvenile idiopathic arthritis, often simply called juvenile arthritis (JA). On average, Black children are more likely to have rheumatoid factor (RF)-positive polyarthritis and less likely to have oligoarticular or early-onset antinuclear antibody (ANA). Black children are also typically older at the onset of the disease than white children, according to a study.
Juvenile arthritis follows three basic patterns. About half of all children with the disease have arthritis in four or fewer large joints, including the knees, ankles, or wrists. Doctors call this oligoarticular arthritis. About 40 percent have arthritis in five or more joints, often in smaller joints like the knuckles or toes. This is known as polyarticular arthritis. There are two types of polyarticular arthritis: polyarticular-RF positive arthritis and polyarticular-RF negative arthritis. This form of arthritis is more likely to last into adulthood.
The final form of juvenile arthritis, called systemic, affects 10 percent of all patients. This condition may strike any number of joints. But systemic arthritis isn't limited to the joints. The inflammation may involve internal organs like the heart and liver and often triggers a light skin rash and a fever.
Juvenile arthritis occurs in children 16 and younger. The disease is more common in girls than boys. According to the American College of Rheumatology, about one child of every 1,000 in the United States has the condition.
You May Also Like
What are the symptoms of juvenile arthritis?
Like other forms of arthritis, JA causes pain, swelling, and joint stiffness. The symptoms often come and go, or, as doctors say, follow a pattern of flare-ups and remission. The condition is often hard for parents to spot. For one thing, many children -- especially young children -- don't complain much about the pain. The most obvious symptom may be stiffness, especially in the early morning or after a long nap. Even a child who wakes up stiff may not tell mom and dad that anything's wrong. Some parents never suspect a problem until they notice their child limping, acting unusually clumsy, or avoiding physical activity.
How is juvenile arthritis diagnosed?
If you think your child might have arthritis, take him or her to a doctor promptly. The doctor will want a detailed description of the symptoms, including when they started. The National Institutes of Health recommends keeping a record of the symptoms as soon as they appear, because "joint swelling or pain must last for at least 6 weeks for the doctor to consider a diagnosis of JA." The doctor may also run tests to rule out other possible causes of joint pain, like infections, Lyme disease, or lupus.
There's no single test for JA, but a doctor can run blood tests to get a better understanding of your child's condition. Some children with severe cases of polyarticular disease have a certain antibody called IgM rheumatoid factor (RF) in their blood. Children with pauciarticular arthritis may have a different marker called antinuclear antibody (ANA). Patients with this antibody are especially likely to develop eye disease.
Another blood test known as a sedimentation rate test (also called a "sed rate" or ESR test) can help detect inflammation. This test looks at how quickly red blood cells, or erythrocytes, settle in a test tube; if some part of the body is inflamed, certain proteins may cause the red blood cells to clump and fall to the bottom of the tube faster than usual.
You May Also Like
However, some children have a normal ESR even though their joints are inflamed. If a doctor thinks the bones may already be
damaged, an x-ray may help determine the extent. Occasionally, doctors can also use x-rays to track cartilage damage early in the disease.
However, about 13 percent of kids have stomach trouble, and there's always a chance that liver damage may occur, though it's much less common in kids than in adults. Many doctors recommend regular liver tests for any child taking the drug. And because methotrexate weakens the immune system, a doctor may refrain from giving live-virus vaccines to a child on the drug. Check with your doctor about other drugs that can be used to treat juvenile arthritis.
As with methotrexate, it pays to be cautious with any medicine that affects the immune system. Many DMARD drugs have a black box warning -- the most serious drug warning the Food and Drug Administration issues.
Children should be current on all of their immunizations before taking the drug, and they shouldn't take the drug within three months of receiving a live-virus vaccine.
To be extra safe, they should briefly stop taking the drug if they've been exposed to chickenpox. (Always check with a doctor before stopping any drug.)
Some biologic drugs, including Enbrel, have also been used as second-line treatments for juvenile arthritis. Enbrel has been associated with certain infections, including tuberculosis; it has also been associated with an increased risk of lymphoma when used in children and teens and has a black box warning, according to the FDA.
In severe cases of JA, doctors might combine powerful drugs called corticosteroids with other treatments. These drugs can dramatically reduce inflammation. However, long-term use of the drugs can cause many serious side effects, including weakened bones and a vulnerability to infections. Once symptoms are under control, a doctor will slowly reduce the dose to lower the risk of complications.
Above all, let your child know that he or she isn't alone. Tell him or her that many children have faced JA -- and many have gotten better.
