Background: The use of cation exchange resins such as sodium polystyrene sulfonate (SPS) in the treatment of hyperkalemia has been associated with potential damage to the gastrointestinal tract. Case Description: We present a clinical case of a 63-year-old male patient admitted following a single-lung transplant who presented a complex postoperative period associating renal failure and hyperkalemia, therefore administering SPS. 17 days afterward, the patient presented a clinical exacerbation with acute abdominal pain, due to a sigmoid perforation. The patient underwent urgent surgery, performing an open sigmoidectomy and terminal colostomy. The anatomo-pathological study of the surgical specimen revealed abundant SPS crystals in the depth of the colonic wall. Conclusions: Close patient surveillance and a high clinical suspicion are essential to prevent potentially fatal complications from the use of SPS. Due to low incidence of this complication, the evidence in literature is limited to case reports and retrospective studies.

Keywords: Sodium polystyrene sulfonate, Cation exchange resins, Intestinal perforation.