In a Bind

Introduction: A 55-year-old woman with suspected Sevelamer-induced colonic ulcer after admission for acute on chronic respiratory failure and an acute kidney injury (AKI). Case Description: A 55-year-old female was admitted for acute respiratory failure and an oliguric AKI due to acute tubular necrosis (ATN) in setting of influenza A infection. She developed hyperphosphatemia (peak phosphorus level of 7.5 mg/dL) which was treated with 1,600mg oral Sevelamer carbonate 3x daily. She was placed on mechanical ventilation and subsequently transferred to an academic center. Within 24 hours of Sevelamer initiation and transfer, the patient experienced multiple episodes of hematochezia. Sigmoidoscopy demonstrated a 15 mm cratered linear ulcer in the cecum opposite the Ileocecal valve. Biopsy showed a single crystalloid structure with a tree-bark appearance and rusty color, consistent with a Sevelamer-induced ulcer. Sevelamer was promptly discontinued, and kidney function improved with supportive measures. Discussion: This case demonstrates the rare finding of a Sevelamer-induced colonic ulcer in the setting of an AKI. Sevelamer is a non-metal hydrogel polymer that binds phosphorus in the GI tract and is widely used to treat hyperphosphatemia; it is generally preferred over calcium-based binders due to reduced risk of hypercalcemia (1). Injury to the gastrointestinal mucosa by direct deposition of Sevelamer crystals is a rare cause of hematochezia and should be considered in any patient taking Sevelamer who presents with intestinal hemorrhage (2). 1. Zeng Q, Zhong Y, Yu X. Meta-analysis of the efficacy and safety of sevelamer as hyperphosphatemia therapy for hemodialysis patients. Vol. 45, Renal Failure. Taylor and Francis Ltd.; 2023. 2. Nambiar S, Pillai UK, Devasahayam J, Oliver T, Karippot A. Colonic Mucosal Ulceration and Gastrointestinal Bleeding Associated with Sevelamer Crystal Deposition in a Patient with End Stage Renal Disease. Case Rep Nephrol. 2018;2018:1–3.Figure 1. Sevelamer-associated colonic ulcer in the setting of an AKI demonstrating characteristic “tree bark” appearance.