In the diagnosis of FUO, what laboratory tests are specific for Systemic Juvenile Idiopathic Arthritis?
None. The laboratory tests demonstrate a chronic inflammatory process. Typically inflammatory markers such as erythrocyte sedimentation rate (ESR) levels are highly elevated. Significant leukocytosis, even to leukemoid levels, is often present with a significant left shift (bandemia). Thrombocytosis is common and thrombocytopenia is atypical. Elevated liver transaminases, aldolase, and ferritin levels can be seen, although this may also be a sign of macrophage activation syndrome (MAS). Creatinine kinase, ANA, and RF are typically normal.
