Clinical Communications
Hyponatremia and seizures in an ultradistance triathlete

https://doi.org/10.1016/S0736-4679(99)00160-2Get rights and content

Abstract

Hyponatremia is being increasingly recognized as a complication of participation in ultra-endurance sports. Reported is the case of an Ironman triathlete who collapsed at the end of the race, having gained 5% in body weight. His serum sodium concentration at the finish was 116 mmol/L. After an Intensive Care Unit course complicated by recurrent seizures, he eventually made a complete neurologic recovery. The pathogenesis of hyponatremia and its management in such cases is discussed.

Introduction

The increasing reports of hyponatremia associated with ultradistance sports over the past 15 years have paralleled the growth in participation in such events 1, 2, 3, 4. Hyponatremia is now recognized as one of the major medical risks of races such as ultradistance triathlons 1, 2, 3, 4, 5. Debate still exists about its pathogenesis and therefore possible methods of prevention and treatment 2, 4, 5, 6, 7. This case is presented to highlight issues around the etiology, presentation, and treatment of this potentially life-threatening disorder.

Section snippets

Case report

A 35-year-old male competitor collapsed having generalized seizures soon after completing an Ironman ultradistance triathlon (3.8-km swim, 180-km cycle, and 42.2-km run). The triathlon had taken him 14 h and 3 min to complete. He previously had been in good health, was taking no medications, and had completed two Ironman triathlons without requiring medical attention.

He had been weighed at registration 2 days before the race and again immediately on finishing, using calibrated Seca scales

Discussion

The subject of this paper suffered severe exercise-associated hyponatremia but survived intact with prompt and appropriate medical care. Many other competitors in the same race were hyponatremic (serum sodium concentrations between 119 to 134 mmol/L) and must be assumed to have been at risk of similar complications, although mild degrees of hyponatremia may be asymptomatic (4). Our work and the work of others suggest that hyponatremia is not unique to this event although it is less common in

Acknowledgements

We gratefully acknowledge the support of the Tom Anderson Memorial Trust.

References (20)

  • A.B. Wolfson

    Acute hyponatremia in ultradistance-endurance athletes

    Am J Emerg Med

    (1995)
  • M. Zehender et al.

    ECG variants and cardiac arrhythmias in athletesclinical relevance and prognostic impor-tance

    Am Heart J

    (1990)
  • A.L. Mulloy et al.

    Hyponatraemic emergencies

    Med Clin North Am

    (1995)
  • T.D. Noakes et al.

    The incidence of hyponatremia during prolonged ultraendurance exercise

    Med Sci Sports Exerc

    (1990)
  • M.L. O’Toole et al.

    Fluid and electrolyte status in athletes receiving medical care at an ultradistance triathlon

    Clin J Sports Med

    (1995)
  • D.B. Speedy et al.

    Hyponatremia and weight changes in an ultradistance triathlon

    Clin J Sport Med

    (1997)
  • D.B. Speedy et al.

    Hyponatremia in ultradistance triathletes

    Med Sci Sports Exerc

    (1999)
  • R.A. Irving et al.

    Evaluation of renal function and fluid homeostasis during recovery from exercise-induced hyponatremia

    J Appl Physiol

    (1992)
  • T.D. Noakes

    Hyponatraemia during endurance runninga physiological and clinical interpretation

    Med Sci Sports Exerc

    (1992)
  • T.D. Noakes

    The hyponatremia of exercise

    Int J Sports Nutr

    (1992)
There are more references available in the full text version of this article.

Cited by (33)

  • Malnutrition and epilepsy: A two-way relationship

    2009, Clinical Nutrition
    Citation Excerpt :

    Electrolyte lab tests are recommended after a first seizure.46,47 Several seizure cases due to hyponatremia have been reported.48–50 A retrospective survey carried out in an American emergency department showed that the incidence of hyponatremia (<126 mmol/L) was responsible for seizure occurrence in 56% of children less than 2 years old and in 70% of children younger than 6 months.51

  • Epidemiology of Hyponatremia

    2009, Seminars in Nephrology
    Citation Excerpt :

    Mild cases of exercise-associated hyponatremia mostly cause nonspecific symptoms, such as headache, nausea, and vomiting.47 However, more severe cases have been associated with seizures, altered mental status, respiratory distress, coma, and death.48-51 These reports highlight the importance of optimizing fluid intake during the prolonged endurance activities to prevent the potentially dangerous consequences of hyponatremia.

  • The Treatment of Hyponatremia

    2009, Seminars in Nephrology
    Citation Excerpt :

    However, as discussed earlier, hourly rates of correction reported in the literature usually are average rates calculated from a beginning serum sodium concentration to an arbitrary target reached many hours later; such calculations obscure the initial rate of correction in the critical first hour or two of therapy. We reviewed the literature to identify reports of hyponatremic patients with seizures or coma in whom data on correction within the first 4 hours were provided90-100 (Table 2). The data suggest that a 4- to 6-mmol/L increase in serum sodium concentration is enough.

  • Malnutrition and epilepsy: Complex links

    2008, Nutrition Clinique et Metabolisme
View all citing articles on Scopus
View full text