Genetic and other Determinants of Sweat Sodium

EICHNER, E.R. Genetic and other determinants of sweat sodium. Curr. Sports Med. Rep., Vol. 7, No. 4, pp. S36-S40, 2008. The purpose of this review is to consider genetic and other determinants of sweat sodium concentration that have practical implications for athletes. The premise is that sweat sodium loss impacts sports performance and that an acute sodium deficit can contribute to "heat cramping" (better termed "sweat cramping"), plasma volume contraction, and hypovolemic hyponatremia. The relevant literature is reviewed and critiqued. Salt-losing genes can predispose athletes to performance and clinical problems because of sodium deficits from heavy sweating. Genetics aside, sweat salt concentration tends to rise in concert with sweat rate. During heat acclimatization, the degree of salt-saving in sweat is influenced by dietary sodium content. Sodium depletion increases sweat salt-saving via the action of aldosterone on sweat glands. Any age or gender differences in sweat sodium concentration seem minor or not of concern for athletic performance. Athletes can learn to increase salt in diet and sports drinks to mitigate performance and clinical consequences of "salty sweating." Inventing a "dipstick" to measure sweat sodium concentration would help us fathom individual sodium needs among athletes. Genetic, dietary, and environmental determinants of sweat sodium concentration have practical implications for the performance and health of athletes.