Testing & Diagnosis for Juvenile Idiopathic Arthritis in Children


The first step in treating your child is forming an accurate and complete diagnosis. There is no foolproof test for whether your child has JIA, which can be frustrating when you want to know so badly what is making your child ill. But the good news is that the doctors who specialize in joint problems, called rheumatologists, can often diagnose JIA by going through your child’s medical history and doing a thorough physical exam.

They may also carry out some blood tests to help determine the type of JIA your child has, or to rule other illnesses. Among the most commonly used tests are:

  • antinuclear antibody (ANA), which can detect proteins called antinuclear antibodies in the blood. These antibodies signal that the body’s immune system is attacking healthy tissue, and they tend to show up in children with JIA (though not all children with JIA have them). They also indicate a higher risk for eye inflammation.
  • rheumatoid factor (RF), which, like ANA, can detect a type of protein associated with immune system problems. In this case, it’s called rheumatoid factor. RF shows up in about 10 percent of children with JIA -- typically those in later childhood or adolescence -- and usually points to a form of polyarticular JIA that’s identical to adult rheumatoid arthritis.
  • anti-cyclic citrullinated peptide (anti-CCP) antibody, a relatively new blood test that, like the RF test, can point to JIA that resembles adult rheumatoid arthritis.
  • erythrocyte sedimentation rate (ESR or sed rate), which measures how quickly red blood cells fall to the bottom of a test tube. If the cells to clump together and fall more rapidly than normal, it can signal there is inflammation (like the inflammation of arthritis) in the body.
  • C-reactive protein (CRP), which measures the levels of a special type of protein produced in the liver. Like the ESR, it’s a marker of inflammation. However, children can have normal CRP or ESR results and still have JIA that could potentially injure their joints or eyes.

Sometimes, doctors want to take a closer look at your child’s actual bones and joints -- either to rule out things like infections, tumors and fractures, or to see what changes JIA may be causing. To do this, they might use such imaging tests as:

  • x-rays, which are good for seeing fractures or other damage to bones, but are less helpful in showing soft tissues, like cartilage.
  • ultrasound, also known as sonography, which uses high-frequency sound waves to create pictures of internal structures. Though ultrasound shows less detail than an MRI, it can be a quick and relatively simple way to check for inflammation in particular joints.
  • magnetic resonance imaging (MRI), which uses a combination of large magnets, radiofrequencies and a computer to produce detailed pictures of the body’s organs, bones and tissues. It lets doctors see how JIA may be affecting the soft tissues of the joint, and is especially useful for joints that are hard to examine physically, like the hip.

But remember: As a parent, you also have a vital part to play in the diagnostic process. When you first meet with your child’s rheumatologist, it’s helpful to bring a list that includes detailed descriptions of your child’s symptoms, any medical problems your child has had or that run in your family, and any medications or supplements your child is taking.

After we complete all necessary tests, our experts meet to review and discuss what they have learned about your child's condition. Then we will meet with you and your family to discuss the results and outline the best treatment options.

When to seek medical advice

If your child has stiffness or swelling in her joints for more than a few weeks -- with or without fever -- it could be a sign of juvenile idiopathic arthritis. You should make an appointment right away with your child’s pediatrician, who will then make a referral to a rheumatologist if JIA is suspected.

A parent’s perspective
Our son, Jack, had just turned 1 and needed your services for an issue he was having with his hip. During our few visits to Boston Children's Hospital, my wife and I were exposed to a whole new world. Read about a family’s experience here at Children’s.