Life threatening hyperphosphataemia after administration of sodium phosphate in preparation for colonoscopy

An elderly woman developed severe hyperphosphataemia, hypocalcaemia, and cardiac arrest after oral administration of sodium phosphate in preparation for colonoscopy. This is an unusual complication and is attributed to decreased phosphate excretion by the kidneys. At increased risk are patients with impaired renal function, age more than 65 years, and presenting with intestinal obstruction or decreased intestinal motility, increased intestinal permeability, liver cirrhosis, or congestive heart failure. Though there are no accepted guidelines for anticipation and prevention of this adverse effect, it may be desirable to check serum phosphate concentrations before choosing the method for colonic preparation and before giving the second oral dose of sodium phosphate in patients at risk. Hyperphosphataemia should be suspected if a patient develops hypotension or neuromuscular irritability after administration of sodium phosphate. Haemodialysis for direct removal of phosphate and intravenous calcium for treatment of symptomatic hypocalcaemia may be life saving.