Hyponatremia in a marathoner

This is the first reported case of hyponatremia associated with increased intracranial pressure, altered mental status, and neurogenic pulmonary edema resulting after a marathon-distance run; the syndrome has been documented previously to occur at distances greater than a marathon. The cause is most likely a combination of salt loss through sweat and retention of high volumes of hypotonic fluids. Preventive measures for the athlete to take include (1) estimating the potential fluid and electrolyte losses before a race and (2) planning a replacement scheme that includes a combination of water and glucose electrolyte solutions. Treatment of the hyponatremia syndrome is primarily supportive and includes infusion of normal saline.