One large body that has considerable experience of the effects of
dehydration and overhydration leading to hyponatraemia is the US military.
In the abstract of his 1999 paper (Mil Med. 1999 Mar;164(3):234-8),
Gardner JW of the Office of the Armed Forces Medical Examiner, Armed
Forces Institute of Pathology, Rockville, MD 20850, USA wrote:
“With recent emphasis on increased water intake during exercise for
the prevention of dehydration and exertional heat illness, there has been
an increase in cases of hyponatremia related to excessive water intake.
This article reviews several recent military cases and three deaths that
have occurred as a result of overhydration, with resultant hyponatremia
and cerebral edema. All of these cases are associated with more than 5 L
(usually 10-20 L) of water intake during a period of a few hours. The
importance of maintaining adequate hydration in exertional heat illness
prevention cannot be overemphasized, but excessive fluid intake may lead
to life-threatening hyponatremia. Current guidelines provide safety by
limiting fluid intake during times of heavy sweating to 1 to 1.5 L per
hour�.
We may conclude from this review that it is as much a medical myth to
state that "an ordinary standard for diverse persons is 1 millilitre for
each calorie of food" as it is to state that we need to drink eight
glasses of water a day. Couch potatoes will need less water to remain
correctly hydrated than will the more active. Moreover, if the general
population is to be encouraged to exercise more, then it is likely that
they may also need to be encouraged to drink more water at either the same
time or shortly following exercise.
Rapid Response:
Hyponatremia
One large body that has considerable experience of the effects of
dehydration and overhydration leading to hyponatraemia is the US military.
In the abstract of his 1999 paper (Mil Med. 1999 Mar;164(3):234-8),
Gardner JW of the Office of the Armed Forces Medical Examiner, Armed
Forces Institute of Pathology, Rockville, MD 20850, USA wrote:
“With recent emphasis on increased water intake during exercise for
the prevention of dehydration and exertional heat illness, there has been
an increase in cases of hyponatremia related to excessive water intake.
This article reviews several recent military cases and three deaths that
have occurred as a result of overhydration, with resultant hyponatremia
and cerebral edema. All of these cases are associated with more than 5 L
(usually 10-20 L) of water intake during a period of a few hours. The
importance of maintaining adequate hydration in exertional heat illness
prevention cannot be overemphasized, but excessive fluid intake may lead
to life-threatening hyponatremia. Current guidelines provide safety by
limiting fluid intake during times of heavy sweating to 1 to 1.5 L per
hour�.
We may conclude from this review that it is as much a medical myth to
state that "an ordinary standard for diverse persons is 1 millilitre for
each calorie of food" as it is to state that we need to drink eight
glasses of water a day. Couch potatoes will need less water to remain
correctly hydrated than will the more active. Moreover, if the general
population is to be encouraged to exercise more, then it is likely that
they may also need to be encouraged to drink more water at either the same
time or shortly following exercise.
Competing interests:
None declared
Competing interests: No competing interests