Advertisement

The “Body Temperature” Myth

  • Philip A. Mackowiak
    Correspondence
    Address correspondence to: Philip A. Mackowiak, Medical Service-111, VA Medical Center, 10 N. Green St., Baltimore, MD, 21201
    Affiliations
    Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
    Search for articles by this author
Published:November 06, 2022DOI:https://doi.org/10.1016/j.amjmed.2022.10.018
      When a patient's temperature is taken, an attempt is made to determine the thermal status of the body as a whole. Is the temperature of the body normal, high or abnormally low? How does the site at which the temperature is taken – mouth, rectum, axilla, skin, tympanic membrane – influence the determination of the normal range? And how should temperatures be reported?
      Interpreting a patient's temperature is more complicated than it might seem, owing to the fact that the temperature varies depending on the anatomical site at which it is taken, sometimes to a marked degree. Rectal temperatures, for example, are on average 1.07°C (2°F) higher than simultaneously obtained axillary temperatures

      Geneva II, Cuzzo B, Fazili T, Javaid W. Normal body temperature: a systemic review. Open Forum Infect Dis. doi:10.1093/ofid/ofz032.

      . Such variation is important, because it has a role in determining the definition of normal, and in turn, that of fever and hypothermia (see below).
      Unfortunately, little consideration has been given to these issues, even in clinical investigations reported in some of medicine's most prestigious journals. In an analysis of 70 publications with fever in the title and/or abstract appearing in 3 top-tier medical journals (New England Journal of Medicine, JAMA and the Lancet) between 2010 and 2020
      • Mackowiak PA
      • Chevenak FA
      • Grunebaum A.
      Defining fever.
      , my coauthors and I found that a mere 4.3% (3/70) described that location at which patients’ temperatures were taken. Only 27.1% (19/70) gave the minimum temperature used to define a fever.
      This lack of concern for how patients’ temperatures are reported in clinical publications is further illustrated in three recent Clinical Problem Solving articles published in the New England Journal of Medicine
      • Mayfield JJ
      • Hidano D
      • Torres JA
      • et al.
      The young and the breathless.
      • Lee CD
      • Shirey E
      • Guttadauria B
      • Kenyon CC.
      Telescoping the diagnostic process.
      • Denu RA
      • Solomon DH
      • Mitchell RN
      • et al.
      Thinking outside the heart.
      . In all three cases, the authors refer to their patient's temperature as a “body temperature,” with no information provided as to how the measurements were made. There is, of course, an oral temperature, a rectal temperature, an axillary temperature and so on, but no such thing as a “body temperature.” As mentioned above, this is because patients’ temperatures at various anatomical sites differ, one from another, with no one temperature reflecting the status of the body as a whole.
      Although to some this distinction might seem much ado about nothing, it can have a profound effect on the interpretation of a patient's temperature. In the Clinical Problem Solving case of September 1, 2022
      • Lee CD
      • Shirey E
      • Guttadauria B
      • Kenyon CC.
      Telescoping the diagnostic process.
      , for example, the 3-year old child's “body temperature” is given as 100.1°F (37.8°C). If that temperature was taken rectally, it would have been normal (depending on the time of day at which the measurement was taken), whereas if it was an axillary temperature, the child's rectal temperature at the time would have been as much as 2°F (1.07°C) higher or 102.1°F (38.37°C) (see above), indicating the presence of a fever.
      Numerous factors influence the interpretation of the results of temperatures obtained from patients (e.g., circadian variation, gender, type of thermometer used, etc.). However, none is more important than the site at which the measurement is taken. Designating a patient's temperature as a “body temperature” ignores this fundamental principal. When reporting a patient's temperature, the anatomical site at which the measurement was made should always be given. In the absence of such information whether the temperature is normal or not is anyone's guess.

      Funding

      None

      Conflict of Interest

      None I verify that I am the sole and only author.

      References

      1. Geneva II, Cuzzo B, Fazili T, Javaid W. Normal body temperature: a systemic review. Open Forum Infect Dis. doi:10.1093/ofid/ofz032.

        • Mackowiak PA
        • Chevenak FA
        • Grunebaum A.
        Defining fever.
        Open Forum Infect Dis. 2021; 8: 1-2https://doi.org/10.1093/ofid/ofab161
        • Mayfield JJ
        • Hidano D
        • Torres JA
        • et al.
        The young and the breathless.
        N Engl J Med. 2022; 387: 67-73
        • Lee CD
        • Shirey E
        • Guttadauria B
        • Kenyon CC.
        Telescoping the diagnostic process.
        N Engl J Med. 2022; 387: 833-838
        • Denu RA
        • Solomon DH
        • Mitchell RN
        • et al.
        Thinking outside the heart.
        N Engl J Med. 2022; 387: 1309-1316