Effect of bowel preparation with oral sodium phosphate on serum potassium level in patients undergoing colonoscopy under IV anesthesia

Objective: To determine the effect of oral sodium phosphate solution, as a colon preparation agent, on the serum potassium level in patients undergoing colonoscopy under IV anesthesia. Material and Method: Patients set to undergo elective colonoscopy under IV anesthesia (propofol infusion) were recruited to participate in the present study during the period between October 2008 and January 2009. All patients had normal serum potassium level prior to colon preparation, and all ingested 90 ml of sodium phosphate solution one day before colonoscopy. Blood samples for post preparation potassium level determination were taken immediately before administering IV propofol. Baseline data including age, gender, diagnosis, indication for colonoscopy, underlying illness, concurrent medications and serum potassium and creatinine levels were recorded. The serum potassium levels were compared before and after colon preparation, and potentially important baseline risk factors for low potassium levels after colon preparation were determined. Results: In 48 patients, there was a 0.57 mmol/L (from 4.11 to 3.54 mmol/L) average reduction in the serum potassium level after colon preparation. There were no significant adverse events during colonoscopy. No significant risk factors were identified on multivariable linear regression analysis. Conclusion: There was a mild reduction in serum potassium level after colon preparation with oral sodium phosphate solution, which was probably not clinically significant. Prophylactic potassium supplement or routine serum potassium monitoring after oral sodium phosphate colon preparation did not seem to be necessary for this group of patients.