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.A dequate preparation of the colon is essential for satisfactory visualisation of the colonic mucosa. Two agents are commonly used for bowel preparation: polyethylene glycol or sodium phosphate based agents. Polyethylene glycol is a non-digestible, non-absorbable, osmotically balanced solution that cleans the bowel by washout of ingested fluids. Being neutral and iso-osmotic, it yields no net absorption or excretion of water and ions.
1The main disadvantage of colonic cleansing with polyethylene glycol is the bad taste and the need to ingest large volumes of the substance. Dibasic sodium phosphate is a powerful osmotic laxative, requiring ingestion of small volumes of fluid and thus providing an attractive alternative for colonic cleansing. Most studies comparing polyethylene glycol and sodium phosphate preparations showed similar compliance with both preparations, without affecting the quality of bowel cleansing. 1 Sodium phosphate preparations are thought to be safe, though they may induce gastrointestinal adverse effects as well as hyperphosphataemia.2-6 We describe a patient who developed hyperphosphataemia and subsequent cardiac arrest after administration of both oral and rectal sodium phosphate in preparation for colonoscopy.
CASE REPORTA 79 year old woman was admitted to the medical ward for evaluation of watery diarrhoea, epigastric pain and fatigue, which occurred during the preceding two months. There was a 30 year history of diabetes mellitus complicated with peripheral neuropathy as well as truncal obesity, hypothyroidism, non-alcoholic steatohepatitis with cirrhosis, portopulmonary hypertension, and mild chronic renal failure. The patient was regularly taking glibenclamide 5 mg three times day, amitriptyline 10 mg once a day, thyroxine sodium 100 mg once a day, furosemide 40 mg twice a day, isosorbide 5 mononitrate 40 mg twice a day, and amlodipine 10 mg once a day.Her blood pressure on admission was 123/71 mm Hg and heart rate 108 beats/min; the ...
