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Booster Shots

98.6 Is Feeling the Heat

November 19, 2001|ROSIE MESTEL

In this muddled-up world, some people find solace in the order and clarity of numbers (though not one of my colleagues, who used to dream that giant numbers were chasing her). Such folks, if they want to retain their serenity, should not do anything rash--like delve into the medical literature for data on the "normal human body temperature."

I did that last week, even though since childhood 98.6 degrees Fahrenheit (37 degrees Celsius) has been seared into my circuits. Don't fixate on that number, say temperature aficionados Matthew Kluger of the Medical College of Georgia and Dr. Philip Mackowiak of the University of Maryland School of Medicine.

For starters, there is no "normal temperature": Each person has his or her own. Female temperatures are a bit higher than male ones, for instance; old people are a smidge colder than whippersnappers.

"Normal," in any case, changes from hour to hour (we're hottest in the afternoon and coldest in early morning) or with levels of physical exertion--and depends on what part of the body you're talking about. Relatively speaking, the liver is good and hot. Extremities such as fingers are on the icy side.

In fact, 98.6 F isn't even an average figure for human body temperature. Doctors and lay folk still cite the number a lot but it has no real significance, says Mackowiak--except a historical one. Back in the 1800s, German doctor Carl Reinhold August Wunderlich got the 98.6 F number by analyzing more than a million temperatures from 25,000 patients.

That prodigious sample size is especially impressive given what Wunderlich was working with. In his day, thermometers weren't slick gizmos you put in a mouth until a beep went off. The big thermometer he wielded had to be lodged in someone's armpit for 15 to 20 minutes, and then read before you took it out.

But armpit measurements aren't as reliable as mouth readings, and his old-time thermometer was probably calibrated slightly differently than today's.

"We actually got access to a thermometer believed to be one of Wunderlich's," says Mackowiak. "His thermometers were reading high."

Using modern ones, Mackowiak and colleagues came up with a slightly lower average temperature of 98.2 (36.8 C), with "normal" readings as high as 98.9 in the morning and 99.9 in the afternoon.

Fever and Infection

It's clever how the body manages to keep its "normal" temperature. Based on temperature-sensing nerves, the brain tells the body to shiver, sweat, get the heck out of the rain, whatever's appropriate.

But when we get sick, things change. Then the brain deliberately makes the body hotter than normal--and it stubbornly resists interference. Since the 1800s, scientists have known that when people with fevers are dunked in warm baths or cool baths, (their bodies try to get back to the fever temperature, not the normal one.

Why? Mild fevers, it seems, help fight off infections--probably by revving up the body's defenses.

In fact, a veritable Noah's ark of creatures raise their temperatures when infected with bacteria or viruses. Kluger showed years ago that iguanas infected with lizard bacteria deliberately move to bask under heat lamps and work up a lizard fever.

A slew of other studies have similarly shown that moderate fevers reduce the severity of infections. There are even studies suggesting that people who don't take fever-reduction drugs for flu or colds or chicken pox get better faster.

Thus, Kluger and Mackowiak say they're often asked if we should avoid lowering our fevers with aspirin and the like. It's not that simple, they say. Modest fevers (say, 102-103 F) may protect. Very high temperatures endanger life. Plus, points out Kluger, fever-reducing drugs also treat other symptoms such as aches and pains and inflammations. If you're not talking life and death, no harm in treating the aches.

*

If you have an idea for a Booster Shots topic, write to Rosie Mestel at the Los Angeles Times, 202 W. 1st. St., Los Angeles, CA 90012, or rosie.mestel@latimes.com.

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