[Serious risk related to oral use of sodium phosphate solution]

Sodium phosphate solutions are commonly used to cleanse the bowel in preparation for colonoscopy, for barium enema or surgical procedures and eventually for treatment of severe constipation. Though relatively safe, these drugs must be used with caution in patients with kidney disease, small intestinal disorders, or poor gut motility and are prohibited in renal insufficiency and bowel obstruction. Especially elderly patients are at increased risk for phosphate intoxication due to decreased glomerular filtration rate, concomitant medication use, and systemic and gastrointestinal diseases. Sodium phosphate solution could induce by at-risk patients serious electrolyte abnormalities (hyperphosphatemia, hypocalcemia, hypokalemia) and acute kidney injury called acute phosphate nephropathy, which is potentially life-threatening condition with slowly progressive renal insufficiency. This article gives a report on two cases of severe adverse effects after administration of oral sodium phosphate solution: an elderly women who developed increase in serum phosphate with compensatory severe hypokalcemia with tetany; and an elderly man who developed acute phosphate nephropathy following colon preparation prior to colonoscopy and barium enema. Especially in elderly and in patients in whom sodium phosphate solution is contraindicated or should be used with caution, we recommend to use isosmotic macrogol (polyethylene glycol) solution for the bowel cleansing a for the treatment of constipation.