March 3, 2006
4 medical myths are debunked
Some beliefs we hold dear are dead wrong. Here are four myths that may surprise you.
Myth No. 1
The normal oral body temperature is 98.6 degrees Fahrenheit.
Not so, according to the research of Dr. Philip Mackowiak, director of medical care in the Veterans Administration Maryland Health Care System, an infectious disease expert and an amateur medical historian.
The 98.6 temperature myth goes back 150 years to the work of Dr. Carl Wunderlich, a German physician who recorded the temperatures of thousands of patients.
Wunderlich published many findings regarding human body temperature, but the finding that made its way into medical literature in Germany and the United States was that mean temperature of the human body is 98.6.
Mackowiak knows that, in fact, Wunderlich never suggested that there was one normal temperature, that his mean temperature reading of 98.6 just took hold in medical minds.
Mackowiak and two colleagues collected 700 temperatures from 148 healthy adults and found their readings ranged from 96 to 100.8. When they figured the average, they found it to be 98.2 degrees with just 8 percent of their 700 temperature readings coming up 98.6.
In 1992, in an article in the Journal of the American Medical Association, Mackowiak and his colleagues concluded that 98.6 should be abandoned.
Mackowiak kept up his research and had the good fortune of locating one of Wunderlich’s thermometers in a museum in Philadelphia.
Mackowiak took the thermometer to Baltimore, where he discovered it was calibrated a degree-and-a-half centigrade higher than the ones used today. Wunderlich also measured temperatures by taking them in the armpit, which should have made them lower than oral temperatures.
This further buttressed the findings from Mackowiak’s earlier study.
Mackowiak has said that the important message isn’t that 98.6 is wrong but that normal temperature depends on the person and can be influenced by age, gender, race and time of day.
In the JAMA article, Mackowiak and his colleagues suggested an oral temperature higher than 99 in the early morning and 100 degrees in the early evening can be called fever.
Myth No. 2
You lose most of your body heat through your head.
The popular belief that most of the body’s heat escapes through the head has prompted parents to urge their children to wear a hat on cold winter days.
The belief stems from military experiments done about 50 years ago in which researchers dressed their subjects in Arctic survival suits and exposed them to frigid conditions. The suits covered their bodies from the neck down so most of their body heat escaped through their heads.
But Dr. Daniel I. Sessler, former professor of anesthesiology, University of Louisville, and now chairman, department of outcomes research, Cleveland Clinic Foundation, determined that if you did the same experiment with people wearing swimsuits, the subjects would only lose about 10 percent of their heat through their heads.
Sessler, an expert on hypothermia has shown that the amount of heat released by any part of the body depends largely on its surface area. On a cold day, you would lose more heat through an exposed arm or leg than your head.
The face, head and upper chest are up to five times as sensitive to changes in temperature as other areas, according to Sessler, thus creating the illusion that covering up those areas traps in more heat. However, covering another part of the body does just as much to reduce overall heat loss.
Myth No. 3
Cough syrups relieve the coughing that is the result of a cold.
Last month, the American College of Chest Physicians began advising people who have colds not to waste their money on over-the-counter cough syrups or drops for themselves or their children.
In an article in the February issue of the journal Chest, chest doctors who reviewed scores of studies concluded that there is no scientific evidence that suppressants, such as dextromethorphan, or expectorants, drugs such as guaifenesin that thin out mucus, relieve coughs when they result from colds.
Richard Irwin, professor of medicine at the University of Massachusetts Medical School, said over-the-counter cough medicines have been shown to have a strong placebo effect. He also says that coughs from colds eventually go away on their own.
The work of a guidelines committee chaired by Irwin jibed with a 2004 report by the Cochrane Collaboration, a nonprofit group that views scientific evidence for medical treatments. That report concluded: “There is no good evidence for or against the effectiveness of over-the-counter medicines in acute cough.”
Myth No. 4
The smallpox vaccination you got as a child protects you for life.
A smallpox vaccination provides a high level of immunity for three to five years and decreasing immunity thereafter.
If a person is vaccinated again later, immunity lasts even longer, according to the U.S. Department of Health and Human Resources’ Centers for Disease Control and Prevention.
Routine smallpox vaccination among the American public stopped in 1972 after the disease was eradicated in the United States.
Until recently, the U.S. government provided vaccine only to a few hundred scientists and medical professionals working with smallpox and similar viruses in research settings.
After September and October 2001, the U.S. government, in taking further actions to prepare for terrorist attacks, updated and released a smallpox response plan.
Right now, the government has access to enough smallpox vaccine to effectively respond to a smallpox outbreak in the United States.
Reporter Linda Stahl can be reached at (502) 582-4666.
Sources: University of Maryland, University of Louisville, Centers for Disease Control and Prevention, USA Today, New York Times