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Created page with 'While dehydration can be dangerous, the danger from Hyponatremia is far greater. Hyponatremia is where the sodium (salt) levels in the blood becomes too dilute. ==Symptoms== Ini…'
While dehydration can be dangerous, the danger from Hyponatremia is far greater. Hyponatremia is where the sodium (salt) levels in the blood becomes too dilute.
==Symptoms==
Initial symptoms tend to be a gain in weight and a general swelling and 'puffiness', most noticeable in the hands. More severe symptoms are caused by a swelling of the brain (cerebral edema) including nausea, vomiting, headache and malaise <ref name="ref10"/>.
==Causes==
The cause of Hyponatremia is poorly understood, but commonly believed to be related to excessive water intake <ref name="ref1"/>. However, I would argue that Hyponatremia is caused excessive fluid intake in the absence of sufficient electrolytes. Hyponatremia can be common in endurance athletes:
* In a 1997 Ironman triathlon, almost 4% of competitors received attention for Hyponatremia <ref name="ref4"/>.
* In a study of the 2002 Boston Marathon, 13% of finishers had some level of Hyponatremia, and 0.6% had critical Hyponatremia <ref name="ref2"/>.
==Risk Factors==
The study revealed that the risk factors for Hyponatremia include
* A slow finish time (>4 hour)
* Consumption of >6 pints (3 liters) of water during the race
* BAA suggests a 'slight build' is also a risk factor<ref name="ref12"/>.
Healthy kidneys can excrete about 2 pints (1 liter) of fluid per hour, but this may be reduced by exertion or illness <ref name="ref3"/>. So drinking >6 pints in 4 hours could easily exceed the kidneys capacity to cope. The recent rise in Hyponatremia may be due to earlier advice to athletes to "drink as much as possible" <ref name="ref13"/>, combined with a general concern about salt intake.
== References ==
<references>
<ref name="ref1">Exercise-Associated Hyponatremia
[http://cjasn.asnjournals.org/cgi/content/abstract/2/1/151 http://cjasn.asnjournals.org/cgi/content/abstract/2/1/151]
</ref>
<ref name="ref10">Hyponatremia
[http://en.wikipedia.org/wiki/Hyponatremia http://en.wikipedia.org/wiki/Hyponatremia]
</ref>
<ref name="ref2">Hyponatremia among Runners in the Boston Marathon
[http://content.nejm.org/cgi/content/abstract/352/15/1550 http://content.nejm.org/cgi/content/abstract/352/15/1550]
</ref>
<ref name="ref4">Micronutrient Information Center - Sodium
[http://lpi.oregonstate.edu/infocenter/minerals/sodium/ http://lpi.oregonstate.edu/infocenter/minerals/sodium/]
</ref>
<ref name="ref13">USATF Announces Major Changes in Hydration Guidelines for Long Distance Runners
[http://www.rrm.com/archive03/042803n2.htm http://www.rrm.com/archive03/042803n2.htm]
</ref>
<ref name="ref3">Water Intoxication
[http://en.wikipedia.org/wiki/Water_intoxication http://en.wikipedia.org/wiki/Water_intoxication]
</ref>
<ref name="ref12">BAA - HYDRATION, DEHYDRATION AND HYPONATREMIA
[http://www.bostonmarathon.org/BostonMarathon/WelcomeBooklet.asp#hydration http://www.bostonmarathon.org/BostonMarathon/WelcomeBooklet.asp#hydration]
</ref>
</references>
==Symptoms==
Initial symptoms tend to be a gain in weight and a general swelling and 'puffiness', most noticeable in the hands. More severe symptoms are caused by a swelling of the brain (cerebral edema) including nausea, vomiting, headache and malaise <ref name="ref10"/>.
==Causes==
The cause of Hyponatremia is poorly understood, but commonly believed to be related to excessive water intake <ref name="ref1"/>. However, I would argue that Hyponatremia is caused excessive fluid intake in the absence of sufficient electrolytes. Hyponatremia can be common in endurance athletes:
* In a 1997 Ironman triathlon, almost 4% of competitors received attention for Hyponatremia <ref name="ref4"/>.
* In a study of the 2002 Boston Marathon, 13% of finishers had some level of Hyponatremia, and 0.6% had critical Hyponatremia <ref name="ref2"/>.
==Risk Factors==
The study revealed that the risk factors for Hyponatremia include
* A slow finish time (>4 hour)
* Consumption of >6 pints (3 liters) of water during the race
* BAA suggests a 'slight build' is also a risk factor<ref name="ref12"/>.
Healthy kidneys can excrete about 2 pints (1 liter) of fluid per hour, but this may be reduced by exertion or illness <ref name="ref3"/>. So drinking >6 pints in 4 hours could easily exceed the kidneys capacity to cope. The recent rise in Hyponatremia may be due to earlier advice to athletes to "drink as much as possible" <ref name="ref13"/>, combined with a general concern about salt intake.
== References ==
<references>
<ref name="ref1">Exercise-Associated Hyponatremia
[http://cjasn.asnjournals.org/cgi/content/abstract/2/1/151 http://cjasn.asnjournals.org/cgi/content/abstract/2/1/151]
</ref>
<ref name="ref10">Hyponatremia
[http://en.wikipedia.org/wiki/Hyponatremia http://en.wikipedia.org/wiki/Hyponatremia]
</ref>
<ref name="ref2">Hyponatremia among Runners in the Boston Marathon
[http://content.nejm.org/cgi/content/abstract/352/15/1550 http://content.nejm.org/cgi/content/abstract/352/15/1550]
</ref>
<ref name="ref4">Micronutrient Information Center - Sodium
[http://lpi.oregonstate.edu/infocenter/minerals/sodium/ http://lpi.oregonstate.edu/infocenter/minerals/sodium/]
</ref>
<ref name="ref13">USATF Announces Major Changes in Hydration Guidelines for Long Distance Runners
[http://www.rrm.com/archive03/042803n2.htm http://www.rrm.com/archive03/042803n2.htm]
</ref>
<ref name="ref3">Water Intoxication
[http://en.wikipedia.org/wiki/Water_intoxication http://en.wikipedia.org/wiki/Water_intoxication]
</ref>
<ref name="ref12">BAA - HYDRATION, DEHYDRATION AND HYPONATREMIA
[http://www.bostonmarathon.org/BostonMarathon/WelcomeBooklet.asp#hydration http://www.bostonmarathon.org/BostonMarathon/WelcomeBooklet.asp#hydration]
</ref>
</references>
