Just when you think you know something  

Anybody with children knows how quickly plans get thrown out the window when a kid wakes up with a fever (for those without, any childcare or school plan is destroyed…rapidly).  So, knowing where your kid is relative to the 98.6-degree cut-off can become quite a focal point.

This week we learned that the age-old “normal” body temperature of 98.6 is not necessarily as iron-clad as we thought. The 98.6 threshold became the standard based on research conducted on 25,000 patients in 1869 by Carl Wunderlich, a German physicist. Today, however, that number is no longer accurate. From the Wall Street Journal:

“In a new study, researchers from Stanford University argue that Wunderlich’s number was correct at the time but is no longer accurate because the human body has changed. Today, they say, the average normal human-body temperature is closer to 97.5 degrees Fahrenheit.”

This is actually quite a change and researchers are now advocating for adjustments to “medical norms and guidelines and thresholds for interventions.”  Researchers are not quite sure why body temperatures have declined, but hypothesize that it is due to changes in metabolic rate (on average, people today are taller and fatter).  The change may also be because people are generally healthier now than they were in the 1800’s (the average life expectancy in 1869 was 38 years). From the researchers:

“For his study, he did try to measure the temperatures of healthy people, she said, but even so, life expectancy at the time was 38 years, and chronic infections such as gum disease and syphilis afflicted large portions of the population. Dr. Parsonnet suspects inflammation caused by those and other persistent maladies explains the temperature documented by Wunderlich and that a population-level change in inflammation is the most plausible explanation for a decrease in temperature.”

We wrote a couple of years ago about how using averages as a guide for making decisions can be deceiving. After all, we all know the story of the person who drowned in water that was – on average – 2 inches deep.  Apart from the fact that now we have no idea when to keep our kids home from school, our reading this week reminded us even a data point that holds true for centuries can change, and we must all be ready to adapt accordingly.