Core body temperature v peripheral body temperature

Core body temperature is the temperature of the body’s internal organs

A normal body temperature ranges between 36.5 and 37.4°C, but temperature readings vary, depending on where it is measured.

  • Core body temperature refers to the temperature of the body’s internal organs, such as the heart, liver, brain and blood.
  • Accurate measurement of core body temperature involves invasive medical procedures in hospital so it is a person’s peripheral body temperature (their ‘skin level’ temperature) that is commonly measured in non-invasive sites such as the mouth, ear, armpit and (less frequently) rectum because these areas are easily accessible and are believed to provide the best estimation of the core body temperature.
  • Despite this, there can be as much as 1 – 2 degrees difference between the actual core body temperature and a peripheral temperature measurement. The armpit temperature tends to be the least accurate because there are no main blood vessels in the armpit area.
  • Digital electronic oral and ear thermometers have largely replaced glass mercury thermometers as the instruments of choice for measuring temperature.
  • Factors that can affect the accuracy of peripheral body temperature measurements include:
    • Mouth - recent ingestion of food or fluid, smoking and having a respiratory rate >18 per minute
    • Ear - build-up of ear wax
    • Armpit - environmental temperature and perspiration
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