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.  
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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. For more details see [[The Science Of Hydration]] and [[Practical Hydration]].
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==Symptoms==
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=Symptoms=
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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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In athletes, mild Hyponatremia may have no clinical symptoms, or weakness, dizziness, headache, nausea/vomiting, but more severe Hyponatremia is likely to have symptoms of cerebral edema, including altered mental status, seizures, pulmonary edema, coma, and death<ref name="RosnerKirven2006"/>. The link between Hyponatremia and [[Cramps]] is not clear, but there is evidence that increased sodium intake can alleviate both problems.
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=Causes=
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==Causes==
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The cause of Hyponatremia is poorly understood, but there appear to be several likely causes in runners.  
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The cause of Hyponatremia is poorly understood, but there appear to be two likely causes in runners.  
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# Excessive water intake can cause 'dilutional Hyponatremia'<ref name="RosnerKirven2006"/>. 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 &gt;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.
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# Excessive water intake can cause 'dilutional Hyponatremia'<ref name="ref1"/>. 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 &gt;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.
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# [[Sodium Deficiency]], combined with adequate or excessive hydration.
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# For ultrarunners, I would argue that Hyponatremia is more likely to be caused by a insufficient electrolytes combined with appropriate drinking.  
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# [[NSAIDs and Running|NSAID]] usage, which is been linked to hyponatremia.
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==Likelyhood==
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# Syndrome Of Inappropriate Antidiuretic Hormone Hypersecretion (SIADH) is where the body secretes too much of the hormone (vasopressin) that reduces the urine output of the kidney. It's not clear if this is an independent cause of hyponatremia, or if this is a mechanism underlying one of the other causes. However, some research<ref name="SiegelVerbalis2007"/> suggests that many cases of Hyponatremia are due to SIADH caused by a combination of over hydration, NSAID usage and Rhabdomyolysis. One key aspect of SIADH is that because it prevents urine production, people mistakenly assume that they are not urinating due to dehydration and drink even more.  
 +
=Likelyhood=
 
Hyponatremia can be common in endurance athletes:
 
Hyponatremia can be common in endurance athletes:
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* In a 1997 Ironman triathlon, almost 4% of competitors received attention for Hyponatremia <ref name="ref4"/>.  
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* In a 1997 Ironman triathlon, almost 4% of competitors received attention for Hyponatremia <ref name="ref4"/>.
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* 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"/>.  
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* In a study of the 2002 Boston Marathon, 13% of finishers had some level of Hyponatremia, and 0.6% had critical Hyponatremia <ref name="Almond-2005"/>.
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* 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.  
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* 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.
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* However, a study<ref name="nzmarathon"/> of the 2002 Christchurch Marathon in New Zealand, where aggressive hydration was not recommended, none of the 134 runners measured had Hyponatremia.  
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* However, a study<ref name="nzmarathon"/> of the 2002 Christchurch Marathon in New Zealand, where aggressive hydration was not recommended, none of the 134 runners measured had Hyponatremia.
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==Risk Factors==
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=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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* A slow finish time (&gt;4 hour)  
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* A slow finish time (&gt;4 hour)
 
* Consumption of &gt;6 pints (3 liters) of water during the race
 
* Consumption of &gt;6 pints (3 liters) of water during the race
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* BAA suggests a 'slight build' is also a risk factor  
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* BAA suggests a 'slight build' is also a risk factor
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==Preventing Hyponatremia==
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=Preventing Hyponatremia=
 
The key to preventing Hyponatremia is to ensure adequate electrolyte intake and to drink when thirsty. See [[Practical Hydration]].
 
The key to preventing Hyponatremia is to ensure adequate electrolyte intake and to drink when thirsty. See [[Practical Hydration]].
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=References=
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== References ==
 
 
<references>
 
<references>
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<ref name="ref1">Exercise-Associated Hyponatremia
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<ref name="RosnerKirven2006">M. H. Rosner, J. Kirven, Exercise-Associated Hyponatremia, Clinical Journal of the American Society of Nephrology, volume 2, issue 1, 2006, pages 151–161, ISSN [http://www.worldcat.org/issn/1555-9041 1555-9041], doi [http://dx.doi.org/10.2215/CJN.02730806 10.2215/CJN.02730806]</ref>
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[http://cjasn.asnjournals.org/cgi/content/abstract/2/1/151 http://cjasn.asnjournals.org/cgi/content/abstract/2/1/151]
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<ref name="Almond-2005">CS. Almond, AY. Shin, EB. Fortescue, RC. Mannix, D. Wypij, BA. Binstadt, CN. Duncan, DP. Olson, AE. Salerno, Hyponatremia among runners in the Boston Marathon., N Engl J Med, volume 352, issue 15, pages 1550-6, Apr 2005, doi [http://dx.doi.org/10.1056/NEJMoa043901 10.1056/NEJMoa043901], PMID [http://www.ncbi.nlm.nih.gov/pubmed/15829535 15829535]</ref>
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</ref>
 
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<ref name="ref10">Hyponatremia
 
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[http://en.wikipedia.org/wiki/Hyponatremia http://en.wikipedia.org/wiki/Hyponatremia]
 
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</ref>
 
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<ref name="ref2">Hyponatremia among Runners in the Boston Marathon
 
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http://content.nejm.org/cgi/content/abstract/352/15/1550
 
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</ref>
 
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<ref name="ref4">Micronutrient Information Center - Sodium
 
<ref name="ref4">Micronutrient Information Center - Sodium
 
[http://lpi.oregonstate.edu/infocenter/minerals/sodium/ http://lpi.oregonstate.edu/infocenter/minerals/sodium/]
 
[http://lpi.oregonstate.edu/infocenter/minerals/sodium/ http://lpi.oregonstate.edu/infocenter/minerals/sodium/]
 
</ref>
 
</ref>
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<ref name="ref13">USATF Announces Major Changes in Hydration Guidelines for Long Distance Runners
 
<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]
 
[http://www.rrm.com/archive03/042803n2.htm http://www.rrm.com/archive03/042803n2.htm]
 
</ref>
 
</ref>
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<ref name="ref3">Water Intoxication
 
<ref name="ref3">Water Intoxication
 
http://en.wikipedia.org/wiki/Water_intoxication
 
http://en.wikipedia.org/wiki/Water_intoxication
 
</ref>
 
</ref>
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<ref name="ref12">BAA - HYDRATION, DEHYDRATION AND HYPONATREMIA
 
<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>
 
</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>
 
<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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<ref name="nzmarathon">Study of hematological and biochemical para... [Clin J Sport Med. 2004] - PubMed - NCBI http://www.ncbi.nlm.nih.gov/pubmed/15523206</ref>
 
<ref name="nzmarathon">Study of hematological and biochemical para... [Clin J Sport Med. 2004] - PubMed - NCBI http://www.ncbi.nlm.nih.gov/pubmed/15523206</ref>
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<ref name="SiegelVerbalis2007">Arthur J. Siegel, Joseph G. Verbalis, Stephen Clement, Jack H. Mendelson, Nancy K. Mello, Marvin Adner, Terry Shirey, Julie Glowacki, Elizabeth Lee-Lewandrowski, Kent B. Lewandrowski, Hyponatremia in Marathon Runners due to Inappropriate Arginine Vasopressin Secretion, The American Journal of Medicine, volume 120, issue 5, 2007, pages 461.e11–461.e17, ISSN [http://www.worldcat.org/issn/00029343 00029343], doi [http://dx.doi.org/10.1016/j.amjmed.2006.10.027 10.1016/j.amjmed.2006.10.027]</ref>
 
</references>
 
</references>
 +
[[Category:Advanced]]
 +
[[Category:Science]]

Latest revision as of 07:56, 25 June 2015

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. For more details see The Science Of Hydration and Practical Hydration.

1 Symptoms

In athletes, mild Hyponatremia may have no clinical symptoms, or weakness, dizziness, headache, nausea/vomiting, but more severe Hyponatremia is likely to have symptoms of cerebral edema, including altered mental status, seizures, pulmonary edema, coma, and death[1]. The link between Hyponatremia and Cramps is not clear, but there is evidence that increased sodium intake can alleviate both problems.

2 Causes

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

  1. Excessive water intake can cause 'dilutional Hyponatremia'[1]. Healthy kidneys can excrete about 2 pints (1 liter) of fluid per hour, but this may be reduced by exertion or illness [2]. 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" [3], combined with a general concern about salt intake.
  2. Sodium Deficiency, combined with adequate or excessive hydration.
  3. NSAID usage, which is been linked to hyponatremia.
  4. Syndrome Of Inappropriate Antidiuretic Hormone Hypersecretion (SIADH) is where the body secretes too much of the hormone (vasopressin) that reduces the urine output of the kidney. It's not clear if this is an independent cause of hyponatremia, or if this is a mechanism underlying one of the other causes. However, some research[4] suggests that many cases of Hyponatremia are due to SIADH caused by a combination of over hydration, NSAID usage and Rhabdomyolysis. One key aspect of SIADH is that because it prevents urine production, people mistakenly assume that they are not urinating due to dehydration and drink even more.

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 marathon[7], 21 runners who received medical help were suffering from Hyponatremia. Runners with Hyponatremia were generally slower and drank more.
  • However, a study[8] of the 2002 Christchurch Marathon in New Zealand, where aggressive hydration was not recommended, none of the 134 runners measured had Hyponatremia.

4 Risk Factors

The study[9] revealed that the risk factors for Hyponatremia in marathons 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 Preventing Hyponatremia

The key to preventing Hyponatremia is to ensure adequate electrolyte intake and to drink when thirsty. See Practical Hydration.

6 References

  1. ↑ 1.0 1.1 M. H. Rosner, J. Kirven, Exercise-Associated Hyponatremia, Clinical Journal of the American Society of Nephrology, volume 2, issue 1, 2006, pages 151–161, ISSN 1555-9041, doi 10.2215/CJN.02730806
  2. ↑ Water Intoxication http://en.wikipedia.org/wiki/Water_intoxication
  3. ↑ USATF Announces Major Changes in Hydration Guidelines for Long Distance Runners http://www.rrm.com/archive03/042803n2.htm
  4. ↑ Arthur J. Siegel, Joseph G. Verbalis, Stephen Clement, Jack H. Mendelson, Nancy K. Mello, Marvin Adner, Terry Shirey, Julie Glowacki, Elizabeth Lee-Lewandrowski, Kent B. Lewandrowski, Hyponatremia in Marathon Runners due to Inappropriate Arginine Vasopressin Secretion, The American Journal of Medicine, volume 120, issue 5, 2007, pages 461.e11–461.e17, ISSN 00029343, doi 10.1016/j.amjmed.2006.10.027
  5. ↑ Micronutrient Information Center - Sodium http://lpi.oregonstate.edu/infocenter/minerals/sodium/
  6. ↑ CS. Almond, AY. Shin, EB. Fortescue, RC. Mannix, D. Wypij, BA. Binstadt, CN. Duncan, DP. Olson, AE. Salerno, Hyponatremia among runners in the Boston Marathon., N Engl J Med, volume 352, issue 15, pages 1550-6, Apr 2005, doi 10.1056/NEJMoa043901, PMID 15829535
  7. ↑ 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
  8. ↑ Study of hematological and biochemical para... [Clin J Sport Med. 2004] - PubMed - NCBI http://www.ncbi.nlm.nih.gov/pubmed/15523206
  9. ↑ BAA - HYDRATION, DEHYDRATION AND HYPONATREMIA http://www.bostonmarathon.org/BostonMarathon/WelcomeBooklet.asp#hydration
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