Hyponatremia among Runners in the Boston Marathon

Abstract

backgroundHyponatremia has emerged as an important cause of race-related death and life-threatening illness among marathon runners. We studied a cohort of marathon runners to estimate the incidence of hyponatremia and to identify the principal risk factors. methods Participants in the 2002 Boston Marathon were recruited one or two days before the race. Subjects completed a survey describing demographic information and training history. After the race, runners provided a blood sample and completed a questionnaire detailing their fluid consumption and urine output during the race. Prerace and postrace weights were recorded. Multivariate regression analyses were performed to identify risk factors associated with hyponatremia. resultsOf 766 runners enrolled, 488 runners (64 percent) provided a usable blood sample at the finish line. Thirteen percent had hyponatremia (a serum sodium concentration of 135 mmol per liter or less); 0.6 percent had critical hyponatremia (120 mmol per liter or less). On univariate analyses, hyponatremia was associated with substantial weight gain, consumption of more than 3 liters of fluids during the race, consumption of fluids every mile, a racing time of >4:00 hours, female sex, and low body-mass index. On multivariate analysis, hyponatremia was associated with weight gain (odds ratio, 4.2; 95 percent confidence interval, 2.2 to 8.2), a racing time of >4:00 hours (odds ratio for the comparison with a time of <3:30 hours, 7.4; 95 percent confidence interval, 2.9 to 23.1), and body-mass-index extremes.conclusions Hyponatremia occurs in a substantial fraction of nonelite marathon runners and can be severe. Considerable weight gain while running, a long racing time, and bodymass-index extremes were associated with hyponatremia, whereas female sex, composition of fluids ingested, and use of nonsteroidal antiinflammatory drugs were not.

Plasma Drug Concentrations and Physiological Measures in ‘Dance Party’ Participants

“…It is possible that this individual increased his fluid intake in an effort to prevent rhabdomyolysis, as has been advocated by some authors. Given recent evidence that such increases in fluid can be dangerous in marathon runners, another group that sometimes uses this practice as a preventative measure (Almond et al, 2005), advice on fluid intake among MDMA users may warrant reconsideration.…”

Hyponatremia Treatment Guidelines 2007: Expert Panel Recommendations

“…34 In marathon runners, low body mass index, race time exceeding 4 hours, consumption of fluids every mile, following advice to "drink as much as possible" during the race, and greater frequency of urination during the race have all been associated with EAH; in some but not all studies, female sex and the use of nonsteroidal anti-inflammatory drugs also were risk factors. 12 Thus, while athletes with both normonatremia and hypernatremia often are dehydrated, most runners with EAH are overhydrated as a result of excessive and perhaps ill-advised water ingestion over an extended race time during which water excretion is limited by osmotically stimulated AVP secretion. 35,36 Low solute intake.…”

Exercise-Associated Hyponatremia

“…However, recent studies have shown that endurance athletes not uncommonly develop hyponatremia at the end of the race, usually in the absence of clear central nervous system symptoms (9,10,12,(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25). For example, in the 2002 Boston Marathon, Almond et al (15) found that 13% of 488 runners studied had hyponatremia (defined as a serum sodium concentration of 135 mmol/L or less) and 0.6% had critical hyponatremia (serum sodium concentration of 120 mmol/L or less). Speedy et al (21) investigated 330 athletes who finished an ultramarathon race.…”