Sevelamer carbonate crystal associated colitis in a hemodialysis patient: a case report

Sevelamer carbonate, a non-calcium phosphate binder widely used in end-stage renal disease (ESRD), is an increasingly recognized but underdiagnosed cause of medication-induced colitis through gastrointestinal crystal deposition. We report a 56-year-old Palestinian male with ESRD on hemodialysis who presented with a one-month history of watery non-bloody diarrhea, vomiting, and diffuse abdominal pain. He had been repeatedly misdiagnosed with amebic colitis and treated with metronidazole without improvement. Colonoscopy revealed diffuse patchy erythema throughout the colon with right-sided predominance. Histopathology confirmed sevelamer-induced active colitis, demonstrating characteristic brownish fish scale-like crystals with active neutrophilic infiltrate. Sevelamer carbonate was discontinued with subsequent clinical improvement. This case highlights a clinically important diagnostic pitfall in resource-limited settings where amebic colitis is endemic and empiric metronidazole is commonly the first-line response to chronic diarrhea in dialysis patients.