Does Choice of Bowel Preparation Method Affect Hyponatremia Risk in Older Patients Readying for Colonoscopy?

Sodium picosulfate, a commonly prescribed medication for bowel prep prior to colonoscopy, is associated with increased risk of hyponatremia in older adults compared to polyethylene glycol.

Medications such as sodium picosulfate and polyethylene glycol used to prepare the bowels of patients scheduled to undergo colonoscopy are associated with risk of severe hyponatremia in some older patients, though there is little data on whether one option is associated with higher risk.

To clarify the risk of hyponatremia in patients using these bowel preparations, the authors of “Hyponatremia and Sodium Picosulfate Bowel Preparations in Older Adults,” published in The American Journal of Gastroenterology, looked at the health records in six databases of all residents of Ontario, Canada, over the age of 65 years who filled an outpatient bowel preparation prescription before colonoscopy.

There were 99,237 patients who filled a prescription for sodium picosulfate and 48,595 who filled one for polyethylene glycol. Patient demographics, comorbid conditions, and concomitant medications were nearly identical between the two groups.

Primary outcome measure was hospitalization with hyponatremia within 30 days of the bowel prep. Secondary outcomes included all-cause mortality and hospitalization with urgent head CT (which the authors identified as a “proxy for acute central nervous system disturbance”).

Analysis of the data revealed that use of sodium picosulfate was associated with a higher risk of hospitalization with hyponatremia compared with polyethylene glycol. However, sodium picosulfate was not associated with greater risk of urgent head CT or mortality.

These findings led the authors to conclude that although sodium picosulfate bowel preparations lead to more hyponatremia than polyethylene glycol, there is no evidence of increased risk of acute neurologic symptoms or mortality. They wrote that “the absolute increase in risk of hospitalization with hyponatremia remains low but may be avoidable through appropriate fluid intake or preferential use of polyethylene glycol in some older adults.”