Three Cases of Severe Hyponatremia During a River Run in Grand Canyon National Park

Abstract

We present 3 cases of severe hyponatremia occurring on a commercially guided river rafting trip on the Colorado River in Grand Canyon National Park. All 3 women appeared to have been overhydrating because of concern about dehydration and required evacuation within 24 hours of each other after the staggered onset of symptoms, which included fatigue and emesis progressing to disorientation or seizure. Each was initially transferred to the nearest hospital and ultimately required intensive care. Imaging and laboratory data indicated all 3 patients had hypervolemic hyponatremia. Unlike the well-documented exercise-associated hyponatremia cases commonly occurring in prolonged endurance athletic events, these 3 unique cases of acute hyponatremia were not associated with significant exercise. The cases illustrate the diagnostic and treatment challenges related to acute hyponatremia in an austere setting, and underscore the importance of preventive measures focused on avoidance of overhydration out of concern for dehydration.

Physiology and Pathophysiology in Ultra-Marathon Running

“…Fluid overload can lead to exercise-associated hyponatremic encephalopathy with severe consquences (Frizzell et al, 1986 ). Several cases of long-distance runners with symptomatic exercise-associated hyponatraemia with altered behavior, seizures and edema are known (Bruso et al, 2010 ; Hoffman and Myers, 2015 ; Pearce et al, 2015 ). Excessive hydration during exercise also has negative effects on the volume of the feet.…”

Exercise-Associated Hyponatremia in Endurance and Ultra-Endurance Performance–Aspects of Sex, Race Location, Ambient Temperature, Sports Discipline, and Length of Performance: A Narrative Review

“…With the formation of cerebral edema at a plasma sodium concentration of <120 mmol/L, symptoms such as headache, confusion, agitation, coordination problems, and unconsciousness can occur [9,12]. Several cases of long-distance runners with symptomatic EAH are known that include altered behavior, seizures and edema [24,94,95,96,97]. When the plasma sodium concentration decreases to <110–115 mmol/L, symptoms such as muscle twitching, disorientation, coma, and epileptic seizures can occur.…”

“…EAH, however, is not limited to long-distance runners or triathletes. Descriptions of hyponatremia in soldiers [108,109], yoga [8,110], bowling [111], tennis [112], American football [13,113], rugby [114], river rafting [96], hiking [115,116], trekking [117], spinning [118], and rowing [119] do exist. Surprisingly, symptomatic EAH can also occur in children [120] and adolescents who are exercising with moderate intensities [98].…”

Description of Three Female 24-h Ultra-Endurance Race Winners in Various Weather Conditions and Disciplines

“…Sex-hormones may influence fluid balance parameters during the luteal phase of the menstrual cycle (57,66) and all three female athletes competed during the ten days of their luteal phase of the menstrual cycle. According to a statement of the Third International Exercise-associated Hyponatremia Consensus Development Conference (31), smaller individuals are more likely to develop EAH adjusted for the BMI and racing time, but sex difference was not statistically significant (8).…”