colonic necrosis has been described as a rare complication after the administration of kayexalate [ 1 , 2 ] . in this case study , we present a case of calcium polystyrene sulfonate - induced colonic necrosis and perforation to remind clinicians of this rare , but dangerous , toxicity associated with this commonly used medication . a 78-year - old woman with stage 4 chronic kidney disease ( ckd ) due to chronic pyelonephritis , and a right hypoplastic kidney was presented to our emergency department with a 2-day history of abdominal pain . her medical history included epilepsy that was treated with carbamazepine , hypertension and hyperlipidaemia , for which she received carvedilol and atorvastatin . because of the persistent hyperkalaemia , she was treated with calcium polystyrene sulfonate at 30 g / day ( anti - potassium granule ; assos drug , istanbul , turkey ) . as a result of the ckd , she was prescribed calcitriol for a mineral and bone disorder , darbepoetin alpha for anaemia and sodium hydrogen carbonate for acidosis . upon initial physical examination , her abdomen was non - distended with normoactive bowel sounds , but there was diffuse tenderness in her abdomen . significant laboratory values at the time of admission included sodium 138 meq / l , potassium 4.6 meq / l , ph 7.20 , bicarbonate 13 meq / l , blood urea nitrogen 71 mg / dl , creatinine 2.6 mg / dl , leukocytes 15 500/mm , eosinophils 110/mm , haematocrit 32.7% , platelets 221 000/mm and c - reactive protein 10.9 mg / dl . on the second day of hospitalization , the abdominal pain worsened and free air under the diaphragm was found on abdominal radiography . her sigmoid colon was found to be necrotic and perforated . a biopsy was performed and the perforated segment was repaired by primary closure . the surface of the deep ulcer contained necroinflammatory debris and various sized fragments of basophilic crystalloid material with angulated margins on microscopic examination ( figure 1a and b ) . also , there were no features of chronic colitis , including inflammatory bowel disease or chronic ischaemic colitis . ( a ) the basophilic crystalloid material in the necroinflammatory background of the ulcer surface ( haematoxylin and eosin , original magnification , 100 ) . ( b ) the basophilic crystalloid material in the necroinflammatory background of the ulcer surface ( haematoxylin and eosin , original magnification , 400 ) . sodium polystyrene sulfonate can also bind intraluminal calcium , leading to constipation , fecal impaction and subsequent bowel obstruction or perforation . gerstman et al .   reported a 0.27% overall incidence , with a higher incidence ( 1.8% ) during the postoperative period . sorbitol enemas , along with experimental evidence suggesting that the necrosis was due to sorbitol rather than the kayexalate in presence of uraemia . extensive transmural necrosis was noted in rats receiving enemas of sorbitol or kayexalate in sorbitol in both the uraemic and non - uraemic groups . as in this case report , renal failure may be an important facilitating factor in the pathogenesis of the necrosis . in contrast to the experimental data , our case was treated with calcium polystyrene sulfonate orally , not rectally . rashid et al . noted that kayexalate in sorbitol given as an enema or orally to treat hyperkalaemia has been reported to induce intestinal necrosis in uraemic patients . they studied clinical and pathologic features of 15 patients and observed kayexalate crystals in tissue specimens from surgical resections and endoscopic biopsies . one possibility is elevated renin levels , commonly seen in renal insufficiency , that predispose the patient to non - occlusive mesenteric ischaemia via angiotensin - mediated vasoconstriction . one gram of kayexalate possesses a theoretical in vitro exchange capacity of 23.1 meq of potassium and in vivo capacity of 1 meq . emmett et al .   reported that in vivo potassium - binding capacity may be lower than previously estimated , more on the order of 0.40.8 meq / g of kayexalate resin . in contrast to other minor digestive complications associated with kayexalate treatment , colonic perforation results in significant morbidity and mortality . as a result , potassium exchange resins may , although rarely , induce a colonic perforation , and this diagnosis should be considered in a patient treated as such in case of acute abdomen . the clinicians must be aware of the possible rare and serious complications of potassium exchange resins .
sodium or calcium polystyrene sulfonate ( kayexalate or analog ) is an ion - exchange resin commonly used to treat hyperkalaemia in patients with chronic kidney disease . 
 it is known to cause digestive complications , such as nausea , vomiting and constipation . 
 although rare , colonic necrosis and perforation are very severe complications associated with the medication . in this case report , we present a case of calcium polystyrene sulfonate - induced colonic necrosis and perforation to remind clinicians of this rare , but dangerous , toxicity associated with this commonly used medication .