[Disorders of water- and electrolyte balance in a triathlon. 2 case reports and review of the literature].

: Triathlon is an increasingly popular sport. The number of active triathletes in Switzerland has increased greatly in recent years. We report two participants of the Zurcher Euroman. Triathlon 1995, who presented with clinically significant water and electrolyte disturbance. The race took place on a hot day and both athletes ingested large amounts of hypoosmolar fluids during and in case 1, after the competition. Case 1 was a 27 year old woman who developed generalized seizures one hour after finishing the race. She had confusion which persisted for several hours. The initial serum sodium concentration was 118 mmol/L. Case 2 was a 29 year old man who collapsed during the triathlon and was confused for hours afterwards. He presented with a serum sodium concentration of 120 mmol/L. Both patients had massive polyuria (first hour urine output of 900 ml, and 1300 ml respectively) that decreased in parallel with the normalization of the serum sodium. The pathophysiology, differential diagnosis and therapy of electrolyte and water disturbances in triathletes is discussed in relation to our two cases and the literature is reviewed.