A blood test is an important diagnostic tool for Still's Disease. Generally, a complete blood count (CBC) is performed to assess for any abnormal changes in the number of red and white blood cells, as well as the number of platelets. Additionally, a blood chemistry panel is done to evaluate the levels of electrolytes, liver and kidney function, and inflammation markers, such as C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR).
In addition, a rheumatoid factor (RF) test is performed to detect autoantibodies, which can be present with Still's Disease. Antinuclear antibody (ANA) testing is done to detect antibodies that attack healthy cells, and antineutrophil cytoplasmic antibody (ANCA) testing is done to detect antibodies that attack neutrophils. Tests may also be done to measure levels of ferritin, which is a protein involved in iron metabolism.
It is important to note that blood tests alone are not enough to diagnose Still's Disease; they are only used to help support a diagnosis. Other diagnostic tests, such as imaging studies or a biopsy, may be done to confirm the diagnosis.