Diagnosis

Diagnosis of juvenile idiopathic arthritis can be difficult because joint pain can be caused by many different types of problems. No single test can confirm a diagnosis, but tests can help rule out some other conditions that produce similar signs and symptoms.

Blood tests

Some of the most common blood tests for suspected cases include:

• Erythrocyte sedimentation rate (ESR). The sedimentation rate is the speed at which your red blood cells settle to the bottom of a tube of blood. An elevated rate can indicate inflammation. Measuring the ESR is primarily used to determine the degree of inflammation.
• C-reactive protein. This blood test also measures levels of general inflammation in the body but on a different scale than the ESR.
• Antinuclear antibody. Antinuclear antibodies are proteins commonly produced by the immune systems of people with certain autoimmune diseases, including arthritis. They are a marker for an increased chance of eye inflammation.
• Rheumatoid factor. This antibody is occasionally found in the blood of children who have juvenile idiopathic arthritis and may mean there's a higher risk of damage from arthritis.
• Cyclic citrullinated peptide (CCP). Like the rheumatoid factor, the CCP is another antibody that may be found in the blood of children with juvenile idiopathic arthritis and may indicate a higher risk of damage.

In many children with juvenile idiopathic arthritis, no significant abnormality will be found in these blood tests.

Imaging scans

X-rays or magnetic resonance imaging may be taken to exclude other conditions, such as fractures, tumors, infection or congenital defects.

Imaging may also be used from time to time after the diagnosis to monitor bone development and to detect joint damage.