Variation in Normal Ear Temperature.

BACKGROUND Variation in baseline ear temperature, taken in the unadjusted mode, has yet to be established in different age groups. Because normal body temperatures show large variations, the same may be expected for increased temperatures in fever. The aims were to study variations in normothermic body temperatures measured with an ear thermometer and to determine differences between actual and perceived body temperature during a febrile episode (referred to as difftemp) in apparently healthy children and adults. METHODS Ear temperature was measured once in 2,006 individuals (61.7% females): 683 children aged 2 and 4 years, 492 adolescents aged 10-18 years, 685 adults aged 19-65 years and 146 elderly aged 66-89 years. Difftemp was estimated as the difference between the individual's ear body temperature, measured in the present study, and the respondent's reported temperature when feverish. RESULTS Mean ear temperature was 36.4 ± 0.6°C overall and in the child and adult groups. In adolescents, it was 36.5 ± 0.5°C, and in elderly, 36.1 ± 0.5°C. Temperature in men was 36.3 ± 0.6°C, and in women, 36.5 ± 0.5°C. Difftemp was 1.1 ± 0.7°C in adolescents, 1.5 ± 0.7°C in children and adults, and 1.6 ± 0.7°C in those >65 years. CONCLUSIONS Ear body temperature is lower than traditionally reported and differs with age and sex. An individual difftemp of 1.0-1.5°C along with malaise might indicate fever.