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Symptomatic hyponatremia during prolonged exercise in heat.
Med Sci Sports Exerc. 1993 May; 25(5):543-9.MS

Abstract

Although hyponatremia (HN) has been reported among endurance athletes, its etiology often remains uncertain and of great interest to clinicians and physiologists. This case report presents physiologic evidence regarding the etiology and development of HN during exercise in the heat. A 21-yr-old male volunteer (K.G.) unexpectedly experienced symptomatic HN during a research investigation that involved controlled sodium (Na+) intake (137 mEq Na+.d-1 for 7d) and exercise-heat acclimation (41 degrees C; 30 min.h-1, 8 h.d-1 for 10 d). Fluid balance, physiologic variables, and hematologic/hormone data were measured before and after the HN episode, with similar measurements recorded for nine unaffected volunteers. The results indicated: 1) HN was verified in K.G. (plasma Na+ < 130 mEq.l-1) after only 4 h of mild, intermittent exercise in heat; 2) K.G.'s heart rate, rectal temperature, blood pressure, and Na+ losses in sweat and urine were < or = control subjects at all times; 3) between hours 4-7, an inappropriately large release of vasopressin coincided with a decrease of urine volume to 0 ml.h-1. It was concluded that a large intake (10.3 l.7h-1) and retention (2.77 l.7h-1) of water and a "low normal" initial plasma Na+ (134 mEq.l-1) were primary factors in the development of HN in K.G., whereas Na+ losses in sweat and urine were normal and served only to exacerbate HN.

Authors+Show Affiliations

U.S. Army Research Institute of Environmental Medicine, Natick, MA 01760-5007.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Case Reports
Journal Article
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

8492680

Citation

Armstrong, L E., et al. "Symptomatic Hyponatremia During Prolonged Exercise in Heat." Medicine and Science in Sports and Exercise, vol. 25, no. 5, 1993, pp. 543-9.
Armstrong LE, Curtis WC, Hubbard RW, et al. Symptomatic hyponatremia during prolonged exercise in heat. Med Sci Sports Exerc. 1993;25(5):543-9.
Armstrong, L. E., Curtis, W. C., Hubbard, R. W., Francesconi, R. P., Moore, R., & Askew, E. W. (1993). Symptomatic hyponatremia during prolonged exercise in heat. Medicine and Science in Sports and Exercise, 25(5), 543-9.
Armstrong LE, et al. Symptomatic Hyponatremia During Prolonged Exercise in Heat. Med Sci Sports Exerc. 1993;25(5):543-9. PubMed PMID: 8492680.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Symptomatic hyponatremia during prolonged exercise in heat. AU - Armstrong,L E, AU - Curtis,W C, AU - Hubbard,R W, AU - Francesconi,R P, AU - Moore,R, AU - Askew,E W, PY - 1993/5/1/pubmed PY - 1993/5/1/medline PY - 1993/5/1/entrez SP - 543 EP - 9 JF - Medicine and science in sports and exercise JO - Med Sci Sports Exerc VL - 25 IS - 5 N2 - Although hyponatremia (HN) has been reported among endurance athletes, its etiology often remains uncertain and of great interest to clinicians and physiologists. This case report presents physiologic evidence regarding the etiology and development of HN during exercise in the heat. A 21-yr-old male volunteer (K.G.) unexpectedly experienced symptomatic HN during a research investigation that involved controlled sodium (Na+) intake (137 mEq Na+.d-1 for 7d) and exercise-heat acclimation (41 degrees C; 30 min.h-1, 8 h.d-1 for 10 d). Fluid balance, physiologic variables, and hematologic/hormone data were measured before and after the HN episode, with similar measurements recorded for nine unaffected volunteers. The results indicated: 1) HN was verified in K.G. (plasma Na+ < 130 mEq.l-1) after only 4 h of mild, intermittent exercise in heat; 2) K.G.'s heart rate, rectal temperature, blood pressure, and Na+ losses in sweat and urine were < or = control subjects at all times; 3) between hours 4-7, an inappropriately large release of vasopressin coincided with a decrease of urine volume to 0 ml.h-1. It was concluded that a large intake (10.3 l.7h-1) and retention (2.77 l.7h-1) of water and a "low normal" initial plasma Na+ (134 mEq.l-1) were primary factors in the development of HN in K.G., whereas Na+ losses in sweat and urine were normal and served only to exacerbate HN. SN - 0195-9131 UR - https://www.unboundmedicine.com/medline/citation/8492680/Symptomatic_hyponatremia_during_prolonged_exercise_in_heat_ L2 - https://Insights.ovid.com/pubmed?pmid=8492680 DB - PRIME DP - Unbound Medicine ER -