Measuring locations that are considered to be reliable: Temple (forehead),Axilar (under the arm), Oral (under the tongue), and Rectal.
Due to the body temperature regulation and different tissue structure it is clinically accepted that there may be up to 0.5-1.5 °C differences between the measurements in the different locations. Learning one’s typical temperature at any of these locations is necessary for effective body temperature monitoring. Clinical references show that the average difference between Under Arm measurement and Rectal measurement is 0.9°C. Moreover, this difference is smaller when the measured person is healthy and it may increase when body temperature rises. Oral measurement may be 0.5°C lower than Rectal measurement. When measuring Orally, placing the thermometer’s probe in the heat pocket, next to the lower molar teeth is essential for accuracy. Differences in readings may vary as much as 0.9°C from the rear sublingual heat pocket to beneath the tongue in front of the floor of the mouth.
Another reason for temperature variance between body locations is because the Rectum fails to track rapid changes in body temperature (such as after taking medication for bringing the fever down etc.) and may take up to an hour until the temperature fluctuations are noticed in rectal measurement. In the mouth or axilla, changes are noticed faster.
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