Hyponatremic Coma after Bowel Preparation

Colonoscopy is a useful tool in modern medicine and is increasingly employed for both diagnostic and treatment purposes. However, bowel preparations can cause electrolyte imbalance, with the risk apparently related to the type of bowel cleansing solution used, the age of the patient and their comorbidities. Symptomatic hyponatremia, especially coma, is a rare complication of oral bowel preparation for colonoscopy and is thought to result from excessive antidiuretic hormone secretion.

The authors report the case of a 48-year-old man who developed symptomatic hyponatremia (coma) after bowel preparation with sodium picosulfate/magnesium oxide/citric acid prior to a colonoscopy. The patient was admitted to an intensive care unit where other causes of coma were excluded. The symptoms of hyponatremia rapidly resolved after sodium level correction with intravenous administration of hypertonic saline.

Hyponatremic coma is an uncommon but serious complication of colonoscopy bowel preparation. Patients at risk (>65 years old, chronic kidney disease, heart failure, history of electrolyte problems, or taking thiazide diuretics, angiotensin-converting-enzyme inhibitors or antidepressants) should be closely monitored during bowel cleansing and macrogol-based solutions should preferably be used.

The association between coma and hyponatremia should be kept in mind when patients undergo bowel preparation, especially if they have chronic kidney disease, heart failure, a history of electrolyte problems or are taking diuretics or antidepressants.Patients should be closely monitored (and their metabolic profile checked before bowel cleansing) and a low threshold maintained for investigation and treatment initiation in case of symptom development.Medications with the potential to cause fluid and electrolytes disturbances such as diuretics and antidepressants should be stopped or reduced in dose while the patient is undergoing bowel preparation.