[Dilutional hyponatremia and convulsions after strenuous exercise]

A 15-year-old girl who drank excessive amounts of water while walking in the desert on a warm day, is reported. Due to complaints of fatigue and headache she was treated with more fluids and had a generalized seizure. On admission her sodium level was 125 meq/l and serum muscle enzymes were increased. Hyponatremia due to exertion and dilution is well established and may be more common than thought. It can present as a generalized seizure and with rhabdomyolysis. This case illustrates the danger of overzealous water replacement, especially without adequate replacement of salts. When water discipline is in force this possibility should be considered in patients presenting after prolonged, strenuous exercise or marching.