A case of Conn's syndrome revealed after oral sodium phosphate (Fleet) preparation for colonoscopy

Oral sodium phosphate solutions (Fleet Mcneil Consumer Healthcare, Guelph, Ontario, Canada) are commonly used as bowel cleansing agents in preparation for colonoscopic exams; however, serious electrolyte disorders associated with oral sodium phosphate use have been described in case reports including hyperphosphatemia, hypocalcemia, hypomagnesemia, hypernatremia, and hypokalemia. We describe a 57-year-old patient with a past history of resistant hypertension who experienced severe symptomatic hypokalemia following colonic cleansing with an oral sodium phosphate solution. Further investigations revealed a serum aldosterone of 691 pmol/L and a serum renin level of 0.02 ng/L/s with a corresponding aldosterone-to-renin ration of 34550:1. The patient was subsequently diagnosed with primary aldosteronism secondary to an adenoma of the adrenal gland. Bilateral adrenal venous sampling revealed excessive levels of aldosterone in the left adrenal vein prior to definitive surgery. This case indicates that an oral sodium phosphate bowel preparation, though safe for most patients, can be complicated by a previously not diagnosed endocrine disease like the primary aldosteronism (Conn's syndrome) reported here. This is the first report of a Conn's syndrome diagnosed after bowel cleansing with a sodium phosphate solution.