Temperatura normal es menor

¿El mundo se calienta y el cuerpo se enfría?

February 4, 2020

It's Time to Abandon 98.6°F (37°C)

Richard T. Ellison III, MD reviewing Protsiv M et al. eLife 2020 Jan 7

Analysis of changing U.S. body temperature measurements over time found a progressive decline in average normal body temperature of 0.03°C per birth decade.

Every grade schooler can tell you that normal body temperature is 98.6°F (37°C), information drawn from Wunderlich's 1851 study of axillary temperature measurements in 25,000 German patients. However, more recent studies yield an average temperature of 97.9°F (36.6°C). To understand this difference, researchers analyzed 677,423 measurements from three data sets: Union Army veterans of the Civil War (UAVCW) 1862–1930, National Health and Nutrition Examination Survey I (NHANES I) respondents 1971–1975, and the Stanford Translational Research Integrated Database (STRIDE) cohort 2007–2017.

Temperature measurements progressively decreased from the UAVCW cohort to the NHANES I cohort and then to the STRIDE cohort. Across all three cohorts, temperature progressively decreased with increasing age (−0.003°C to −0.0043°C per year). Analysis of NHANE I and STRIDE data confirmed previously reported positive correlations between body-mass index (BMI) and body temperature and between later hour of the day and increased temperatures. Over the 197 birth-year span of the cohorts, temperature steadily decreased 0.03°C per decade in both men and women and in both black and white populations. Analysis of the impact of chronic infectious diseases on body temperature in the UAVCW cohort found that tuberculosis and pneumonia diagnoses were associated with increased body temperature in the absence of fever.

COMMENT

Although axillary temperature measurements are typically lower than oral temperatures, the authors propose that the observed temperature change is unlikely to be caused by measurement variables but rather by physiologic changes. Untreated chronic infections such as syphilis, periodontitis, and tuberculosis were common in Wunderlich's time, and modern heating and cooling systems have likely decreased the physiologic stress of adapting to differing ambient temperatures that could raise resting metabolism. Both factors have likely contributed to lower average body temperatures in today's population.

EDITOR DISCLOSURES AT TIME OF PUBLICATION

Disclosures for Richard T. Ellison III, MD at time of publication

Consult/Advisory Board	Acurx Pharmaceuticals, LLC; Philips Healthcare
Speaker's Bureau	Philips Healthcare
Grant/Research Support	Philips Healthcare

CITATION(S):

Protsiv M et al. Decreasing human body temperature in the United States since the Industrial Revolution. eLife 2020 Jan 7; 9:e49555. (https://doi.org/10.7554/eLife.49555)

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