If you ask us what the “normal” temperature of our body is, the instinctive answer will be 37º Celsius. When the thermometer exceeds that mark, we usually talk about fevermild or high depending on how far we move away from the figure. However, over time health experts have realized that the reality is a little more complex.
The body temperature issue It is not a mere curiosity. Fever is an important response of our body to many diseases or disorders, generally to infections.
The fever It is a double-edged sword: our body raises its temperature to try to kill viruses and bacteria that may be damaging it, while activating our body’s immune response; However, in the process, fever can also put the proper functioning of our organs at risk and cause other problems such as dehydration.
Since fever is a common response to various illnesses, it can also cause us serve as a diagnostic toolto narrow the circle on the possible conditions that affect us.
Answering the question of what is the “normal” temperature of our body is difficult. And the reasons behind this are several.
Firstly, because, over the last century and a half, the estimated average temperature of the human body has been reducing. The notion that our body temperature It is at 37º and dates back to the mid-19th century.
In 1868, the German doctor Carl Reinhold August Wunderlich conducted a study using 25,000 patients and more than a million temperature measurements. From these data, he calculated that the average temperature was 37ºbut also observed certain deviations.
However, more recent studies have observed lower average temperatures. A recent example of this we found it in a studio Made in the United States and published in 2020 in the magazine eLife. The analysis indicated that Americans’ body temperatures had been dropping at a rate of about 0.03º Celsius every decade. A previous study conducted in the United Kingdom and published in 2017 in the magazine B.M.J.estimated an average temperature of 36.6º in its sample of more than 35,000 participants and 250,000 measurements.
We don’t really know why body temperature has been reducing over time. A possible explanation It lies in the improvements in hygiene and immunity, which would imply a lower incidence of infections in the population and therefore lower average temperatures. But this is just one of the various hypotheses that seek to explain the phenomenon.
Wunderlich himself observed in his study that men and older people tended to have lower body temperatures, while women and younger people had higher temperatures on average. Which brings us to the second reason why establishing a “normal” reading is especially difficult. And it depends.
Sex and age are two of the factors that can make what is “normal” for one person not “normal” for another. But other factors can also alter this figure. a study published in 2023 in the magazine JAMA Internal Medicine measured the degree to which these factors affected body temperature, but also added new variables such as height, body mass, and the time of day at which the measurement was taken.
Among the sample of 618,306 observations, the average temperature was at 36.64º Celsius. Among the participants, the average readings for each individual ranged between 36.24º and 36.89º.
It is also worth remembering that there are different ways to measure body temperature (tympanic, oral, axillary…) and that each one It presents some slight associated deviations.
So at what temperature fever comes? As is evident after what we have read, the answer is that it depends on each person and situation, although fortunately, with the variations being less than one degree, the interpretation of the results of a thermometer may not be as different from the conventional one as to affect decisions such as whether or not to stay home during a cold. However, for health experts, having better knowledge about these variables can be of great help.
That is why new studies have also investigated this question. One published in November of last year in the magazine Scientific Reports by South Korean researchers, analyzed the body temperature of 9,195 hospital patients through tympanic temperature measurements (the tympanic temperature It is usually half a degree above the oral measurement and about one degree above the axillary measurement). The team estimated an average temperature of 36.91º Celsius, and a limit of 37.81º for fever.
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Image | Polina Tankilevitch