Greg Glassman and Dr. Timothy Noakes

Tried to convey in my post that I support CrossFit and that I realize the doc knows more than he can share in a snippet. Entire textbooks are written on the subject, so i thought the brevity of the way their arguments were represented was the problem. 

I read the doc’s response to my comment as well. I stand by the following (I won’t explain the difference between dehydration and volume depletion since you’re a physician, other readers can look it up if needed): volume depletion is a powerful drive for ADH release and is the cause for hyponatremia in endurance athletes. Once you replete volume, the drive for ADH shuts off. For almost all endurance athletes, the solution for hyponatremia is volume. Even if the athlete has been drinking water or other hypotonic beverages, and thus has a critically low sodium, normal saline at 154 mEQ of sodium will be hypertonic to the athlete’s blood. And since the volume turns off their ADH, they will be able to excrete free water (unlike a patient with SIADH). If you see a symptomatic athlete at the end of a marathon, draw blood, and diagnose hyponatremia, the rational response is to administer volume. The doc says in his response that, to die from the condition he describes, you would have to have concomitant SIADH, a condition almost always associated with CNS or lung disease, cancer, drugs, or advanced age. If someone fit these categories, you would be more diligent in your sodium work up. Still, unless the athlete carries a known prior diagnosis of SIADH, if their clinics exam suggests hypovolemia, you’re going to administer volume. 

I should say that as an inpatient physician, I’m talking about volume as IV isotonic fluids. I agree that oral fluids could possibly exacerbate the hyponatremia unless an actual oral rehydration solution, which isn’t usually commercially available. 

if I get a chance I will try to find waterlogged and take a look. And again, I’m not detracting one any way from CF, which I’ve been doing since my brother in law preached it after his Special Forces training. And I’ve been practicing conservative, less-is-more, evidence-based medicine since well before that. 

Hi Dr. Derick, Unfortunately you are wrong again. Persons with exercise-associated hyponatremic encephalopathy (EAHE) have marked fluid overload. One patient we studied in our 1991 Journal of Applied Physiology publication had a fluid excess at the end of the race of 6 litres; in those 8 runners with EAHE there was a linear relationship between their fluid excess at the end of the 56-mile Comrades Marathon and their post-race/hospital admission serum sodium concentrations. 

Subsequent studies have confirmed that athletes with hyponatremia have measurable ADH concentrations indicating that they have SIADH (since ADH concentrations should be undetectable in those with fluid overload as you correctly imply). Here's a relevant reference: Siegel A.J., Verbalis J.G., Clement S., Mendelson J.H., Mello N.K., Adner M., Shirey T., Glowacki J., Lee-Lewandrowski E., Lewandrowski K.B. Hyponatremia in marathon runners due to inappropriate arginine vasopressin secretion. Am. J. Med. 2007;120:461.e11–461.e17. doi: 10.1016/j.amjmed.2006.10.027. 

Treating these patients with intravenous solutions that contains less than 3-5% saline would place a physician at risk of a charge of malpractice since they conflict with the Consensus Guidelines of the experts in the field and will produce an adverse outcome in anyone with EAHE and associated SIADH. 

The book Waterlogged records what I learned in the first 30 years I spent studying the condition after describing the world's first case in 1981. 

Please read it as a matter or urgency.
 

Thanks Derrick for your comments. 

I'm "the doctor" in the interview. I was the first person to describe the condition of Exercise-Associated Hyponatremic Encephalopathy (EAHE) in 1985 and with my colleague Dr Tony Irving the first to work out what causes it in 1991. I wrote the definitive book on the condition, Waterlogged, which I would encourage you to read. 

Still to believe that EAHE is caused in those who are "replacing their sodium containing volume lost (i.e. sweat) with non-salt containing volume" unfortunately reflects grievous misunderstanding of the real pathophysiology of the condition. Continuing to promote this misinformation is potentially dangerous it if encourages inappropriate treatment of persons with EAHE.

Without SIADH it is almost certainly impossible to develop EAHE.  The action of ADH on the kidney is to active sodium loss and water retention. Giving intravenous normal (0.9%) saline to anyone who has developed EAHE (as a result of drinking too much during prolonged exercise and inappropriately retaining excess fluid because of SIADH) simply causes additional water retention and sodium loss, further exacerbating the state of gross fluid overload. The most probable outcome will be cerebellar coning through the foramen magnum leading to death from respiratory arrest. On the other hand giving a hyper-concentrated sodium solution (3-5%) intravenously overrides the action of ADH producing an immediate renal sodium diuresis with prompt reversal of even the worst cases of  EAHE within 5-10 hours.

Thank you for giving me the opportunity to include this explanation. The biology of EAHE is well described in our published works and is pretty well described also in the series of columns I wrote for CrossFit Health last year.

Here are some relevant references: 
			
Noakes TD. Comrades makes medical history—again. S.A. Runner (4 Sept. 1981): 8-10.
Noakes TD, Goodwin N, Rayner BL, et al. Water intoxication: a possible complication during endurance exercise. Med Sci Sports Exerc. 17(1985): 370–375.
Irving RA, Noakes TD, Buck R, et al. Evaluation of renal function and fluid homeostasis during recovery from exercise-induced hyponatremia. J Appl Physiol. 70(1991): 342-348.
Noakes TD, Sharwood K, Speedy D, et al. Three independent biological mechanisms cause exercise-associated hyponatremia: Evidence from 2,135 weighed competitive athletic performances. PNAS (102): 18550-18555, 2005.
Noakes TD. Waterlogged: The Serious Problem of Overhydration in Endurance Sports. Champaign, IL: Human Kinetics, 2012.

Yes Katina! Aseem promised that he would. I’ll check up on that. 

Nice to see you and it is inspirational to me too that Dr. Noakes is doing CrossFit. I love his story of getting started.