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J Emerg Med. 2019 Feb;56(2):177-184. doi: 10.1016/j.jemermed.2018.10.026. Epub 2018 Dec 10.

Predicted Risk for Exacerbation of Exercise-Associated Hyponatremia from Indiscriminate Postrace Intravenous Hydration of Ultramarathon Runners.

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Physical Medicine & Rehabilitation Service, Department of Veterans Affairs, Northern California Health Care System, Sacramento, California; University of California Davis Medical Center, Sacramento, California; Ultra Sports Science Foundation, El Dorado Hills, California.



Asymptomatic or mildly symptomatic exercise-associated hyponatremia (EAH) can be exacerbated by aggressive hydration.


This work predicts the percentage of athletes at risk for exacerbation of EAH from indiscriminate hydration after an ultramarathon.


Postrace serum sodium, creatinine, creatine kinase (CK), and urea nitrogen concentrations were determined for 161-km ultramarathon participants. Body mass was measured prior to and immediately after the race. Incidents when serum CK was > 20,000 U/L or creatinine ≥ 1.5 times estimated baseline were considered to be "at risk for receiving I.V. hydration" if presenting to a hospital. Those with EAH without body mass loss during the race were considered "overhydrated" and "at risk for EAH exacerbation."


Among 627 finishers, 16 (2.6%) were at risk for EAH exacerbation. Considering 421 observations at risk for receiving I.V. hydration, 16 (47.1%) of the 34 observations with EAH were at risk for EAH exacerbation. Among those at risk for receiving I.V. hydration and with EAH, serum urea nitrogen and creatine concentration as a multiple of estimated baseline were lower (p < 0.05) for those at risk for EAH exacerbation, compared with those without overhydration, but there were no clinically useful laboratory findings to distinguish these two groups due to considerable overlap of values.


Whether in the field or hospital setting, I.V. hydration of an athlete after an ultramarathon carries a notable risk for exacerbating EAH, so clinicians should use caution when hydrating athletes after endurance events.


acute kidney injury; creatine kinase; creatinine; dehydration; endurance exercise; rhabdomyolysis

[Indexed for MEDLINE]

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