Water Intake

[Denise Krakowski <denisek@mail.wsu.edu>]

Too Much Water Can Harm Marathon Runners

By Amy Norton

NEW YORK (Reuters Health) - When runners collapse or get
sick at the end of a long race, it seems logical to give
them fluids. Sometimes, however, water is the last thing
these athletes need, researchers report.

In the current issue of Annals of Internal of Medicine,
investigators report on marathon runners who developed brain
swelling as a result of ``water intoxication.'' All had
taken in too much water during their races, causing sodium
levels in the blood to drop. From there, according to Dr. J.
Carlos Ayus, excess water is absorbed into blood and fluid
builds up in the brain. Eventually, fluid accumulates in the
lungs, and athletes become breathless and nauseated.

Ayus, a professor of medicine at Baylor College of Medicine
in Houston, Texas, told Reuters Health that when runners
collapse or become ill, the natural assumption may be that
they are having a heart attack. Yet, rather than being a
sign of heart attack, fluid build-up in the lungs--called
pulmonary edema--may signal brain swelling, according to
Ayus.

``I believe,'' he said, ``that this is what happens to many
people who collapse and die after a race. It should be
diagnosed more often now.''

In their report, Ayus and his colleagues describe the cases
of seven marathoners who collapsed and had nausea and
vomiting after their races. When brain scans revealed
swelling, six of the patients were treated with an
intravenous solution containing high amounts of sodium--a
water-depleting treatment that is directly the opposite of
the low-sodium solutions that runners may receive if they
are misdiagnosed, Ayus noted. The seventh patient, who was
not diagnosed with brain swelling, later died; an autopsy
revealed that there had indeed been fluid on the brain.

Five of the patients were female, suggesting that women may
be more prone to water intoxication and its effects on the
brain and lungs. And, Ayus pointed out, all seven had a
history of using nonsteroidal anti-inflammatory
drugs--painkillers that include aspirin. These drugs can
block the excretion of water from the body, he explained.

Whether athletes other than marathoners experience this
series of events is unclear, but Ayus said that it is
possible. Runners who become breathless and nauseated after
drinking large amounts of water during a race should go the
hospital, he advised. There, he added, doctors should check
blood sodium levels.

``The natural response to these symptoms is to drink a lot
of water,'' Ayus said. ``And, yes, you can get into trouble
if you don't get enough water. But too much water can also
cause trouble.''

SOURCE: Annals of Internal Medicine 2000;132:711-714.