The possible beneficial effects of fever have been debated for many years.3 Aside from these considerations, it is important to recognize that fever represents a symptom of some underlying disease, and one must determine what this disease is.
An initial question is "What degree of temperature elevation represents a fever?" One survey conducted among pediatric training programs revealed a wide variability in the temperature considered a "fever" in infants younger than 2 months of age.4 This figure has ranged from 38° to 39.4°C (100.4° to 103°F). It is important to recognize that oral temperatures are generally 0.6°C (1°F) lower than rectal temperatures and axillary temperatures are 0.6°C (1°F) lower than oral temperatures. Temperatures taken using infrared thermometers that scan the tympanic membrane are of variable reliability and reproducibility. 5 Body temperature normally varies from morning to evening with the body's circadian rhythm. The degree of variation, which is greater in young women and small children, is about 1.1°C (2°F).
Current practice guidelines suggest a temperature of 38°C as a sufficient fever to warrant an evaluation. 6 The relationship between height of fever and incidence of bacteremia is discussed below. In general, higher temperatures are associated with a higher incidence of bacteremia. 7 A retrospective study of hyperpyrexia reported that the incidence of meningitis was twice as high in children with fever above 41.1°C (105.9°F), compared with children with fever between 40.5° and 41.0°C (104.9° and 105.8°F).8 The incidence of pneumonia and bacteremia was the same in the two groups.
Other studies, many of which have also been retrospective, have had variable results and indicated that children with higher temperatures have more diagnostic studies ordered but the same incidence of different diseases.91 and I1
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