A curtain-raiser for the upcoming Era of Lowered Expectations: Normal body temperature has been reduced to 98.2 degrees.
A team of medical researchers in Baltimore has determined that 98.6 degrees Fahrenheit -- celebrated in song, medical text and little red lines on thermometers -- is actually a little high to be considered "normal" for adults.
A study of 148 healthy people, published today in the Journal of the American Medical Association, found that 98.2
F was the average temperature throughout the day.
"It's hard to understand how 98.6 has enjoyed such pertinacity for more a century and a half," said Philip A. Mackowiak, a professor of medicine at the University of Maryland School of Medicine and the lead author.
The idea that 98.6
F. is normal temperature arose from the research of a German physician, Carl R. A. Wunderlich, who recorded temperatures of more than 25,000 patients at the University of Liepzig over a period of 16 years. His treatise on the subject was published in 1868. The recent research is the first large-scale measurement of body temperature since then.
In the new study, Mackowiak and his colleagues studied a group of men and women between the ages of 18 and 40, who had their oral temperatures taken several times a day for 2 1/2 days.
The average temperature overall was 98.2. Only 8 percent of the measurements, which were taken with an electronic thermometer, were 98.6.
Women were warmer than men, with an average temperature of 98.4, compared with 98.1 in men. Blacks tended to have slightly higher temperatures than whites, though the trend was not statistically significant.
As in studies in the past, the Baltimore group found that temperature was lowest about 6 a.m., and peaked between 4 p.m. and 6 p.m. The upper limit of normal in the morning was 98.9 degrees, and in the evening, 99.9. Temperatures above those at those times of day can rightly be termed fevers, the researchers said.
"The whole idea should be abandoned that a single temperature has any significance as the 'normal' temperature. One should think of the normal temperature as a range, rather than any particular number," Mackowiak said.
He added that the new measurements were only in adults, and that children and the elderly may have different average temperatures.
The researchers also found little agreement in textbooks and medical dictionaries about what constituted a "fever." Some defined it as anything higher than 98.6; others said fever did not begin until temperature was over 100.4.
"It's hard to believe that we haven't done a better job in formulating these definitions. I was frankly dumbfounded," Mackowiak said.
He added that he is also at a loss to explain how Wunderlich's dogma could have gone unquestioned for so long.
"One explanation is that it's not as easy as it sounds, getting a bunch of normal people in a situation where you can monitor them around the clock for several days," Mackowiak said. "Another explanation is the daunting effect of Wunderlich's data set, which supposedly had over 1 million measurements. Who would want to compete with that?"
More perplexing is the fact that Wunderlich's normal is higher than the newly measured one, even though his method of measurement would tend to get lower-than-normal readings.
Wunderlich took "axillary" readings, in which the thermometer is placed in the armpit, with the arm squeezed down over the bulb. Axillary temperatures are generally lower than oral or rectal temperatures.
The researchers located one of Wunderlich's thermometers, at the Mutter Museum of the College of Physicians in Philadelphia, and made some measurements with it. It consistently registered more than 3 degrees Fahrenheit higher than the electronic thermometers.
"There was a huge discrepancy, but it was in the right direction. Of course, we don't know what happens to thermometers when they sit around for 120 years," Mackowiak said.
The routine measurement of temperature was apparently first done by Anton DeHaen, a physician in Leyden in the mid-1700s, Elisha Atkins, a retired professor of medicine at Yale and medical historian, said yesterday.