History and admission findings: A 45-year-old female presented with somnolence and convulsions after finishing her first ironman triathlon. Besides the neurological symptoms she had a swollen face and swollen ankles. Rales could be heard on pulmonary auscultation. The past medical history was unremarkable. Due to musculoskeletal pain the patient had taken ibuprofen until two days before the race.
Investigations: The laboratory tests showed severe hyponatremia ( 111 mmol/l ) and hypoosmolalitiy of the serum. The osmolality of the urine was high (314 mosm/kg). Radiological examination revealed pulmonary as well as cerebral edema.
Treatment and course: On admission the patient was treated with hypertonic saline which increased the serum sodium concentration. Nevertheless she developed respiratory and hemodynamic failure. She had to be intubated, mechanically ventilated and needed catecholamines. After treatment with furosemide recovery occurred. The patient was extubated and was transferred to a hospital near her home without any neurolgical deficits one week after admission. One year later the former patient was again participant of the ironman triathlon. She was advised not to drink excessively and received oral salt supplementation. This time the athlete finished the race with a serum sodium concentration of 141 mmol/l.
Conclusions: Ultra-endurance exercise can lead to severe hyponatremia, pulmonary and cerebral edema. This is caused mainly by fluid overload due to excesssive drinking and a release of ADH induced by hypovolemia and stress which impairs the excretion of free water. Hence a moderate fluid intake during and after endurance exercise is very important.