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http://www.metrowestdailynews.com/arts_lifestyle/health/siegel11052003.htm
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Marathon mystery: Physician plans to study potential co-factor in
'water-intoxication'
By Michelle Hillman /
News Staff Writer
Dr. Arthur Siegel has already identified the hormone he believes
triggers a mysterious condition that can kill marathon runners who drink too
much water. Now Siegel hopes to study a second hormone that could be a co-factor
causing "water intoxication" -- a rare but serious condition that
killed Waltham resident Cynthia Lucero last year. Lucero was the first to die
of hyponatremia in Boston Marathon history. Another woman, Hilary Bellamy, died a day after she collapsed at mile 22
of last year's Marine Corps Marathon in Washington, D.C., from the same
condition. "What we did with these two samples, we...interrogated these samples
like you would look at a flight data recorder in a plane crash," said
Siegel, chief of internal medicine at McLean Hospital in Belmont. Blood samples from both women have led to Siegel's theory that hormonal
response to a muscle injury, not sodium levels in the blood, causes
hyponatremia. The exact cause of hyponatremia is the focus of debate among medical experts
who do not universally accept Siegel's unpublished research. "What we're trying to do is develop a consensus," Siegel said.
"Everyone agrees it's over-drinking. The point is, we think, from
studying these two cases, really it's not about the salt." The muscle injury sends the body into "red alert" triggering the
brain to send messages to antidiuretic hormones called arginine vasopressine
that tell the kidneys to stop secreting water. The retention combined with
runner's excessive fluid intake dilutes the blood to dangerously low sodium
levels and floods cells. While diluted blood sodium levels are an indication of over-drinking,
Siegel said hormones, not salt, are to blame for the build-up of fluid in the
body. In extreme cases, cells in the brain try to soak up the extra fluid
causing seizures, coma and death from brain swelling. "What we've learned (from Lucero and Bellamy), the excess drinking is
the outside job," he said. "The inside job is the muscle injury
that sets up a hormone response." The danger is that runners like Lucero, who believe they are dehydrated,
continue to drink unaware that the symptoms -- disorientation, dizziness and
nausea -- are the same symptoms of hyponatremia. Siegel is hoping to work with physicians at Georgetown University Hospital
where Bellamy died to determine if other hormones, including one called
oxytocin found in Bellamy's blood, play a role in triggering hyponatremia in
women. Oxytocin is a hormone that causes uterine muscle contraction and lactation
and Siegel said it is not surprising it was found in Bellamy's blood since
she was a nursing mother. Siegel is also investigating hormones that retain fluid during menstrual
cycles. "It might be that menstruating women need to be more careful of how
much fluid they take," he said. Siegel plans to study 100 blood samples collected from runners in the
medical tent at last year's Boston Marathon to look for the hormones he
believes are to blame. Lucero and Bellamy's cases could unlock the mystery of the potentially
fatal and rare condition that is common among women and charity runners, but
can strike anyone who doesn't monitor fluid intake. Often charity runners are
on the course for longer periods of time and drink more fluids. Since the problem is a result of too much fluid rather than not enough
salt, treating the condition by replacing salt by drinking sports drinks like
Gatorade will do more harm, Siegel said. Instead, runners need to stop drinking fluids entirely until the body
releases water by urination, Siegel said. Lucero drank 16 ounces of fluid five minutes before she collapsed, also at
mile 22 during last year's Boston Marathon. The 28-year-old charity runner
died later at Brigham & Women's Hospital, just the second death in race
history. This Sunday , family, friends and fellow runners will gather for the
second annual 5K run/walk in Lucero's memory. The event will be held at the
Massachusetts School of Professional Psychology where Lucero was a doctorate
student. All proceeds go to the "Dr. Cynthia Lucero Center for Health
Psychology at the Massachusetts School of Professional Psychology where
Lucero was finishing her doctorate in clinical psychology. Lucero trained with Rick Muhr, head coach for the Leukemia and Lymphoma's
"Team in Training," of which she was a member. He said he pays
close attention to Siegel's research and cautions runners about over-drinking
and mistaking "intoxication" for dehydration. "The ailments are completely opposite yet the symptoms are exactly
the same," he said. For more information about the run/walk or to volunteer, call the
Massachusetts School of Professional Psychology at at 1-888-664-MSPP. Michelle Hillman can be reached at 508-626-4447 or mhillman@cnc.com.
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