Overview
The diagnosis of JSpA can be difficult because the symptoms are sometimes episodic and unpredictable. However, it is important to get a correct diagnosis as soon as possible in order to begin treatment. This is the role of a pediatric rheumatologist - a physician with special training in diagnosing and treating arthritis in children. It is important to note that even in the care of the most experienced rheumatologist, a diagnosis can involve extensive testing and time.

In order to make the diagnosis, the physician will commonly do a physical exam and evaluate your child's history of symptoms as well as perform laboratory tests. Note that X-rays are seldom useful in the diagnosis of JSpA in that the changes due to spondylitis normally seen in adults are rarely present in children. Moreover, the X-rays can be difficult to interpret in teenagers since the bones are growing along the joints.

Physical Exam
A complete physical exam is commonly performed including evaluating for arthritis; asking careful questions about, and examining for, inflammation/pain - specifically enthesitis - inflammation of the area where a ligament or tendon attaches to the bone. The physician may also test for good spinal mobility and tenderness in the sacroiliac (SI) joints (the joints at the base of the spine, where the spine meets the pelvis), as well as check movement with breathing.

A clinical history of symptoms is also important. This can include checking the family history of AS and related diseases since heredity does play a factor.

Laboratory Tests
It is important to note that there is no specific laboratory test for JSpA. Blood tests show that children with JSpA do not have rheumatoid factor or antinuclear antibodies common in other types of chronic childhood arthritis. Also, a positive test for the HLA-B27 genetic marker correlates with the presence of JSpA in a child with arthritis. The presence of the HLA-B27 genetic marker in spondyloarthropathy varies by race, so while the HLA-B27 test is important, it is not diagnostic for juvenile spondyloarthropathy.

Other Indicators Helpful in Diagnosis
Sometimes, children with JSpA may encounter other problems such as Crohn's disease and ulcerative colitis (inflammation of the intestine), uveitis or iritis (inflammation of the eye) or psoriasis (severe skin rash).