The goals of testing are to help diagnose juvenile rheumatoid arthritis, to distinguish it from other forms of arthritis and conditions with similar symptoms, and to evaluate its severity. Testing can be used to monitor the condition, its potential complications, response to treatment, and to monitor for potential side effects associated with some Treatment.
Diagnosis of JRA is based on review of clinical signs and symptoms, such as persistent arthritis in one or more joints for at least 6 weeks that cannot be attributed to another cause. Patients may also have an enlarged liver or spleen, swollen lymph nodes, anemia, heart problems, and eye inflammation.
Laboratory tests that can aid in the diagnosis of JRA and in ruling out other disorders are:
- Complete blood count (CBC) – to evaluate the child's red and white blood cells and hemoglobin to help evaluate and monitor the condition and complications such as anemia and/or a decreased white blood cell count
- Erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP) – to detect inflammation
- Antinuclear antibody (ANA) – to detect the presence of autoantibodies; most common test to be positive in children with JRA; about 80% of those with eye involvement will test positive for ANA
- Rheumatoid factor (RF) – may be positive or negative depending on the type of JRA
- Comprehensive Metabolic Panel (CMP) – to help evaluate and monitor the child's kidney and liver function
- Blood culture – to rule out infection
- HLA-B27 – to detect this gene, which is present in 70-90% of patients with arthritis affecting the spine
- Synovial fluid analysis – sometimes ordered to detect crystals that may be present in the joint and to look for signs of joint infection
- Other laboratory tests, such as a test for Lyme disease, may be ordered as indicated to rule out other conditions with similar symptoms.
Ferritin levels, though not used to diagnose the condition, may be elevated with JRA.
- X-rays of the joints and chest – to identify the presence of joint inflammation or fluid build-up around the heart or lungs
- Eye exam to detect the development of eye inflammation
- EKG – to detect inflammation of the heart