All children with FUO should have Complete blood count with manual differential Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) Blood cultures Urinalysis and urine culture Chest x-ray Serum electrolytes, blood urea nitrogen (BUN), creatinine, albumin, and hepatic enzymes HIV serology Tuberculin skin test or interferon-gamma release assay The results of these studies in conjunction with findings from the history and physical examination can focus further diagnostic tests.