Chulalongkorn Medical Journal


Background : Colonoscopy is the gold standard investigation for assessing ofthe intra-luminal colorectal pathology. Effective bowel preparationcontributed efficient visualizing of the colon. Osmotic laxatives suchas sodium phosphate (NaP) are commonly used for colonicpreparation for colonoscopy. A meta-analysis suggested that NaPoffered a more effective and more readily completed preparationthan PEG-based regimes. However, the use of sodium phosphatesolution has been shown to significantly reduce the serum potassiumlevel which is likely to affect cardiac rhythm in particular byprolonging the QT interval. But this affect was not clinicallymeaningful in most of patients. Sodium phosphate (NaP) arecommonly used for colonic preparation for colonoscopy in PhukieoRural Hospital a secondary care community hospital, the effect oforal sodium phosphate solution, as a colon preparation agent, onthe serum potassium level in patients undergoing colonoscopy wasevaluated.Objective : To determine the effect of oral sodium phosphate solution, as acolon preparation agent, on the serum potassium level in patientsundergoing colonoscopy.Design : Retrospective cohort study.Setting : Phukieo Rural Hospital, Chaiyaphum ProvinceMaterial and Methods : From January 2010 to December 2013, medical charts of88 patients who were admitted to Phukieo Rural Hospital forcolonoscopy were retrospectively reviewed. All patients were givensodium phosphate solutions as colon preparation agents. Basictests included serum electrolytes (pre- and post-preparation serumpotassium levels) and creatinine determination, electrocardiography(EKG) and chest radiographs. Changes in oxygen saturation, bloodpressure, EKG, and any adverse events occurring duringcolonoscopy were monitored in all patients. The differences betweenthe levels of serum potassium levels before and after colonpreparation were tested for statistical significance.Result : There was a 0.17 mmol/L average reduction in the serum potassiumlevel after colon preparation in 88 patients. No significant adverseevents occurred during colonoscopy. No potential risk factorsassociated with reduced post-sodium phosphate serum potassiumlevels were identified on analysis of covariance. No systematicassociation between post-sodium phosphate potassium levels andany potential risk factors was seen.Conclusion : There was a mild reduction in the level of serum potassium aftercolon preparation with oral sodium phosphate solution in patientswho underwent colonoscopy. The reduction was not clinicallysignificant.


Faculty of Medicine, Chulalongkorn University

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