RT Book, Section A1 Steele, Russell W. A2 Rudolph, Colin D. A2 Rudolph, Abraham M. A2 Lister, George E. A2 First, Lewis R. A2 Gershon, Anne A. SR Print(0) ID 7021859 T1 Chapter 228. Fever of Unknown Origin T2 Rudolph's Pediatrics, 22e YR 2011 FD 2011 PB The McGraw-Hill Companies PP New York, NY SN 978-0-07-149723-7 LK accesspediatrics.mhmedical.com/content.aspx?aid=7021859 RD 2024/04/24 AB The definition of FUO requires an immunologically normal host with oral or rectal temperature ⩾38.0°C (100.4°F) at least twice a week for more than 3 weeks, a noncontributory history and physical examination, and 1 week of outpatient investigation.6-9 Early diagnostic studies normally include a complete blood cell count; lactate dehydrogenase (LDH); uric acid; urinalysis and culture; chest roentgenogram; tuberculin skin test; erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP); and, in the older child, a titer of antinuclear antibodies. Management of patients with comorbidity factors such as acquired or congenital immunodeficiency, neutropenia, and occurrence of fever during prolonged hospital stays is not considered in the following discussion.