THURSDAY, Dec. 23 (HealthDay News) -- Most people think of arthritis as a disease of old age, with people's joints growing creaky and painful later in life.

But arthritis also affects hundreds of thousands of kids in the United States. Children and teens with juvenile arthritis face a lifetime of aching joints and impaired mobility if the disease isn't caught in time.

"There are about 300,000 kids that are affected by juvenile arthritis," said Dr. Patience White, vice president of public health for the Arthritis Foundation and a professor of pediatrics and medicine at George Washington University School of Medicine and Health Sciences. "That means it's more common than kids with type 1 diabetes."

Though the disease itself isn't rare, doctors specially trained to treat juvenile arthritis can be hard to find.

Fewer than 200 certified pediatric rheumatologists currently practice in the United States, making it one of the smallest pediatric subspecialties, according to the U.S. Department of Health and Human Services. Thirteen states don't have a single pediatric rheumatologist within their borders, including heavily populated states such as Arizona, South Carolina and Alabama.

"There are many families who have to travel many miles -- sometimes to another state -- to see a pediatric rheumatologist," White said.

Three types of juvenile arthritis have been identified, according to the Arthritis Foundation and the American Academy of Orthopaedic Surgeons:

• Pauciarticular juvenile arthritis typically affects four or fewer joints. About half of the children with juvenile arthritis have this type. It usually affects the large joints, including the knees, ankles or wrists, and often strikes a joint on one side of the body while leaving the corresponding joint alone.
• Polyarticular juvenile arthritis affects five or more joints. About 30 percent of children with the disease have this type, girls more often than boys. It most often affects the knees, wrists and ankles but also can affect other joints such as the hips, neck, shoulders and jaw.
• Systemic onset juvenile arthritis causes inflammation throughout the body. The child typically suffers from swelling, pain and limited motion in at least one joint, and the disease very often affects the small joints of the hands, wrists, knees and ankles. Internal organs such as the heart, liver and spleen as well as lymph nodes also may become inflamed, and children can develop rashes and fevers of 102 degrees or higher for weeks at a time. About 20 percent of children with juvenile arthritis develop this type, and it affects boys and girls equally.

Any child younger than 18 can develop juvenile arthritis, but there tend to be two age ranges when it's more likely to occur. There's one peak at ages 2 to 4, followed by another peak at ages 8 to 12, said Dr. Harry Gewanter, a pediatric rheumatologist with Pediatric and Adolescent Health Partners in Richmond, Va., and a clinical associate professor of pediatrics and physical medicine and rehabilitation at Virginia Commonwealth University School of Medicine.

"Their hallmark is you have a chronic arthritis that lasts at least six weeks in one or more joints," Gewanter said. "Lots of kids will have problems with their joints that come and go for a variety of reasons, but there are very few things that are going to stick around besides something like this."

It can be difficult for parents to know there's something wrong with their child, however, because kids lack the ability to communicate pain effectively, White said. Most of the time, kids with juvenile arthritis have a limp, but parents generally think that the child hurt a leg or knee.

Parents should suspect juvenile arthritis if they notice the child limping more in the morning or after a nap; that's because the joint grows stiff when it's at rest. The affected joints also will be red and swollen.

Though various laboratory tests can be used to help narrow a diagnosis, there's no one test to identify it. "It's really more a combination of history and the exam and lab tests, and the pattern consistent with this illness," Gewanter said.

Doctors used to try one arthritis drug after another until they found one that worked. These days, he said, they try to shotgun-blast the arthritis as hard as possible after diagnosis.

"We've taken a page from the oncologists in terms of going after this as aggressively as we can at the start," Gewanter said. "We're trying to jump in hard to shut down all the inflammation early, then peel medications away as you can. If you take a child and treat them aggressively straight away, often you can just shut the whole thing down and change the course of the disease. That kind of an approach really has made as much of a difference as anything else."

It can be difficult for parents to find a doctor to provide such treatment, however, because of the shortage of pediatric rheumatologists. White said the shortage developed because the specialists make much less money than a general pediatrician, even though they have to undergo more extensive training.

Federal health-care reform might help solve the situation, though, as one clause in the law creates a loan repayment program for pediatricians who undergo training in a specialty such as rheumatology, White said. They would be granted extensions for their loan repayment.

"We're excited about that," White said, but he added quickly that Congress has not yet funded the program.

More information

The Arthritis Foundation has more on juvenile arthritis.

For more on juvenile arthritis, read about one teenager's story.