A case of severe acute hyponatremia after colonoscopy with polyethylene glycol plus ascorbic acid bowel preparation

Previous reports have shown that bowel preparation can, in extremely rare circumstances, induce severe acute hyponatremia. Polyethylene glycol plus ascorbic acid as a bowel preparation is considered relatively safe with a smaller amount of free water load and a more pleasant taste with additives. We present the case of an 86-year-old man who developed severe acute hyponatremia presenting with tremor and impaired consciousness after colonoscopy, which is life-threatening. The severe hyponatremia in our case was not caused by free water loads from drinking large amounts of water during bowel preparation or hypovolemia due to bowel preparation-induced nausea, vomiting, and diarrhea, but might have been due to non-osmotic stimuli of antidiuretic hormone (ADH) release (i.e., pre-existing nausea, stress, anxiety, pain, stress, or the colonoscopy itself). Our study indicates that it is important to choose safer bowel preparation solutions, to be aware of ingested water volumes, to assess volume status, and also remain aware of other coexisting risk factors for acute hyponatremia, such as medical history, medication, and ADH release, especially in elderly patients.