Monday, November 16, 2009

“Hyponatremia”

There is a Great Article we just posted on the EFC website under Training. It’s called "Hyponatremia"

There has been a great discussion on the USAT coaches group about this and I asked a couple of coaches if I could post the article and one of the comments. I think it provides excellent information and it can help endurance athletes.

Please click here to read the article.

Then read Dr. Andy’s response below…

"It has long been suspected amongst those in the Sports Medicine community that disordered ADH secretion during endurance activity has a large role to play in the hyponatremia associated with extreme endurance sports such as triathlon and marathoning.  Too much ADH means too much water retention and the effective sodium concentration decreases.  How much is real sodium loss is the question.  Events shorter than 4-5 hours I’d lean towards a dilutional problem due to excessive ADH secretion. Events longer than that, I’d assume equal parts of too much ADH and too little sodium.  The fly in the ointment so to speak is how do you explain severe hyponatremia in the community of runners doing 6-7 hour marathons. That one probably entails free water intoxication from stopping at too many water stations. We probably have way too many water stations at races these days from a medical standpoint.

Look at the stats from the early days of marathoning when water stations were limited at best (not every mile as they are now)...almost no hyponatremia was documented only hypernatremia from dehydration. Enter the studies showing performance enhancement with good hydration and you begin to see exertional hyponatremia.  So I think that too much ADH plays a role as does excessive water intake in some and insufficient sodium intake in others.

What to do when hyponatremia is diagnosed in the medical tent AND there are severe symptoms is a subject for one of our Sports Medicine journal clubs and a matter of some debate...more hydration vs. 3% saline infusion.  Most of the exertional hyponatremias and hypernatremias are acute and "usually" can be corrected relatively quickly.  Chronic problems that have lead to some physiologic adaptations (chronic dehydration causes cells to take on more "osmoles" to tolerated a more concentrated blood) can be made worse however with overly rapid correction (central pontine myelinosis).  Bottom line for Sports Docs, stabilize in the med tent (BP, airway, and mental status) with IVF and transport quickly to the ER for further management."

Andrew Hunt, MD

Medical Director, USAT

Thanks Dr. Andrew! Knowledge is power team!

 

Posted by Coach Kelly on 11/16/09 at 11:18 AM
Fitness and Training • (0) Comments • Permalink

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