Acute Severe Hyponatremia with Seizure Following Polyethylene Glycol-Based Bowel Preparation for Colonoscopy

4 liters of polyethylene glycol (PEG) solution is commonly used to evacuate the colon before colonoscopy. This substance, however, is known to cause electrolyte abnormalities such as hyponatremia. Seizures caused by hyponatremia associated with bowel preparation have only rarely been reported. We report the case that a 75-year-old woman with no prior history of seizures was developed severe hyponatremia (112 mEq/L) with generalized tonic-clonic seizure and mental change after ingestion of 4L of PEG solution. Past medical history was notable for thiazide diuretics. Her symptoms are improved during intravenous administration of hypertonic saline for the correction of hyponatremia. Patients with impaired ability to excrete free water those with renal insufficiency, hypothyroidism, mineralocorticoid deficiency, liver cirrhosis, or heart failure as well as those taking drugs which including thiazide diuretics, NASIDs, and ACE inhibitors have risk of hyponatremia following bowel preparation for colonoscopy. We conclude that physicians should check patient's condition and electrolyte abnormalities before colonoscopy procedures.