Kayexalate-Induced Ischemic Colitis: Revisiting a Forgotten but Preventable Cause of Colonic Necrosis

Sodium polystyrene sulfonate (SPS), commonly used to treat hyperkalemia, has rarely been associated with severe gastrointestinal injury.We describe a 72-year-old man with chronic kidney disease on long-term SPS therapy who presented with melena and acute kidney injury requiring hemodialysis.Colonoscopy revealed a large ulcerated lesion in the sigmoid colon.Abdominal CT angiography revealed circumferential sigmoid wall thickening with patent mesenteric arteries, raising suspicion of ischemic colitis.Histological examination showed mucosal ulceration and characteristic basophilic, angulated crystals exhibiting a mosaic-like "fish-scale" pattern on hematoxylin and eosin staining, consistent with SPS deposition and supporting the diagnosis of SPS-induced ischemic colitis.SPS was discontinued, and the patient improved with supportive treatment alone.Awareness of this rare complication is important, as early recognition and drug withdrawal may prevent intestinal necrosis, perforation, and death.