​The diagnosis of JIA is made by taking a detailed medical history, doing a physical examination to look for signs of joint inflammation, and excluding other conditions that can mimic JIA. There is no blood test that can be used to diagnose or confirm JIA.

 Your doctor may perform the following tests to aid in making the diagnosis and to determine the severity of the disease:

• Blood tests to assess the degree of inflammation (e.g., C-reactive protein (CRP), Erythrocyte Sedimentation Rate (ESR), full blood count),
• Autoantibodies (e.g. anti-nuclear antibody, rheumatoid factor)
• X-rays or magnetic resonance imaging (MRI) scans to detect unusual bone development, joint damage and soft tissue abnormalities.