Difference between revisions of "Hyponatremia"

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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.  
 
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==
 
==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"/>.
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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"/>. The link between Hyponatremia and [[Cramps]] is not clear, but there is evidence that increased sodium intake can alleviate the problem.
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==Causes==
 
==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:
 
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:

Revision as of 14:01, 24 April 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 commonly believed to be related to excessive water intake [2]. 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 [3].
  • In a study of the 2002 Boston Marathon, 13% of finishers had some level of Hyponatremia, and 0.6% had critical Hyponatremia [4].

3 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[5].

Healthy kidneys can excrete about 2 pints (1 liter) of fluid per hour, but this may be reduced by exertion or illness [6]. 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" [7], combined with a general concern about salt intake.

4 References

  1. Hyponatremia http://en.wikipedia.org/wiki/Hyponatremia
  2. Exercise-Associated Hyponatremia http://cjasn.asnjournals.org/cgi/content/abstract/2/1/151
  3. Micronutrient Information Center - Sodium http://lpi.oregonstate.edu/infocenter/minerals/sodium/
  4. Hyponatremia among Runners in the Boston Marathon http://content.nejm.org/cgi/content/abstract/352/15/1550
  5. BAA - HYDRATION, DEHYDRATION AND HYPONATREMIA http://www.bostonmarathon.org/BostonMarathon/WelcomeBooklet.asp#hydration
  6. Water Intoxication http://en.wikipedia.org/wiki/Water_intoxication
  7. USATF Announces Major Changes in Hydration Guidelines for Long Distance Runners http://www.rrm.com/archive03/042803n2.htm