[Hyponatremic Seizure after Ingestion of an Oral Sulfate Tablet for Bowel Preparation for Colonoscopy].

The oral sulfate tablet (OST), commercially available as Orafang (Pharmbio Korea Co., Seoul, Korea) in Korea, is being used increasingly because of its bowel-cleansing efficacy, safety, and tolerability in adults undergoing colonoscopy. Other bowel cleansing agents, such as polyethylene glycol and sodium picosulfate/magnesium citrate, can cause plasma volume depletion and electrolyte disturbances, such as hyponatremia. On the other hand, the OST has never been reported to cause hyponatremia in Korea. To our knowledge, the authors experienced the first case of hyponatremic seizure in an 81-year-old woman to whom an OST was administered for bowel preparation before a colonoscopy. After ingesting the OST, she presented with seizure, confusion, and dyspnea. Upon arrival, her serum sodium level was 120 mEq/L, and the urine osmolality and sodium levels were 449 mOsm/kg and 253 mOsm/kg, respectively; chest imaging suggested pulmonary edema. The associated symptoms disappeared following treatment with an intravenous injection of normal saline and 3% NaCl to normalize the sodium level. This case shows that the OST can cause hyponatremia and other severe complications related to hyponatremia.