Difference between revisions of "Hyponatremia"

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* In a 1997 Ironman triathlon, almost 4% of competitors received attention for Hyponatremia <ref name="ref4"/>.  
 
* 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"/>.  
 
* 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"/>.  
 +
* In the Houston marathon<ref name="Houston">, 21 runners who received medical help were suffering from Hyponatremia. Runners with Hyponatremia were generally slower and drank more.
 
==Risk Factors==
 
==Risk Factors==
 
The study<ref name="ref12"/> revealed that the risk factors for Hyponatremia in marathons include  
 
The study<ref name="ref12"/> revealed that the risk factors for Hyponatremia in marathons include  
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<ref name="ref2">Hyponatremia among Runners in the Boston Marathon
 
<ref name="ref2">Hyponatremia among Runners in the Boston Marathon
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[http://content.nejm.org/cgi/content/abstract/352/15/1550 http://content.nejm.org/cgi/content/abstract/352/15/1550]
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http://content.nejm.org/cgi/content/abstract/352/15/1550
 
</ref>
 
</ref>
  
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<ref name="ref3">Water Intoxication
 
<ref name="ref3">Water Intoxication
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[http://en.wikipedia.org/wiki/Water_intoxication http://en.wikipedia.org/wiki/Water_intoxication]
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http://en.wikipedia.org/wiki/Water_intoxication
 
</ref>
 
</ref>
  
 
<ref name="ref12">BAA - HYDRATION, DEHYDRATION AND HYPONATREMIA
 
<ref name="ref12">BAA - HYDRATION, DEHYDRATION AND HYPONATREMIA
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[http://www.bostonmarathon.org/BostonMarathon/WelcomeBooklet.asp#hydration http://www.bostonmarathon.org/BostonMarathon/WelcomeBooklet.asp#hydration]
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http://www.bostonmarathon.org/BostonMarathon/WelcomeBooklet.asp#hydration
 
</ref>
 
</ref>
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<ref name="Houston">Hew TD, Chorley JN, Cianca JC, et al. The incidence, risk factors and clinical manifestations of hyponatremia in marathon runners. Clin J Sports Med. 2003;13:41–47 http://www.ncbi.nlm.nih.gov/pubmed/12544163</ref>
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</references>
 
</references>

Revision as of 16:13, 14 November 2011

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.

1 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 [1]. The link between Hyponatremia and Cramps is not clear, but there is evidence that increased sodium intake can alleviate the problem.

2 Causes

The cause of Hyponatremia is poorly understood, but there appear to be two likely causes in runners.

  1. Excessive water intake can cause 'dilutional Hyponatremia'[2]. Healthy kidneys can excrete about 2 pints (1 liter) of fluid per hour, but this may be reduced by exertion or illness [3]. 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" [4], combined with a general concern about salt intake.
  2. For ultrarunners, I would argue that Hyponatremia is more likely to be caused by a insufficient electrolytes combined with appropriate drinking.

3 Likelyhood

Hyponatremia can be common in endurance athletes:

  • In a 1997 Ironman triathlon, almost 4% of competitors received attention for Hyponatremia [5].
  • In a study of the 2002 Boston Marathon, 13% of finishers had some level of Hyponatremia, and 0.6% had critical Hyponatremia [6].
  • In the Houston marathonCite error: Closing </ref> missing for <ref> tag

[1]

[6]

[5]

[4]

[3]

[7]

[8]

</references>
  1. ↑ 1.0 1.1 Hyponatremia http://en.wikipedia.org/wiki/Hyponatremia
  2. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named ref1
  3. ↑ 3.0 3.1 Water Intoxication http://en.wikipedia.org/wiki/Water_intoxication
  4. ↑ 4.0 4.1 USATF Announces Major Changes in Hydration Guidelines for Long Distance Runners http://www.rrm.com/archive03/042803n2.htm
  5. ↑ 5.0 5.1 Micronutrient Information Center - Sodium http://lpi.oregonstate.edu/infocenter/minerals/sodium/
  6. ↑ 6.0 6.1 Hyponatremia among Runners in the Boston Marathon http://content.nejm.org/cgi/content/abstract/352/15/1550
  7. ↑ BAA - HYDRATION, DEHYDRATION AND HYPONATREMIA http://www.bostonmarathon.org/BostonMarathon/WelcomeBooklet.asp#hydration
  8. ↑ Hew TD, Chorley JN, Cianca JC, et al. The incidence, risk factors and clinical manifestations of hyponatremia in marathon runners. Clin J Sports Med. 2003;13:41–47 http://www.ncbi.nlm.nih.gov/pubmed/12544163
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