Crystals in the Colon: A Surprising Culprit Behind Massive GI Bleeding in End-Stage Renal Disease

A 66-year-old man undergoing medical treatment and hemodialysis for diabetes mellitus–related end-stage renal disease (ESRD) presented to the emergency department with worsening epigastric discomfort and loose stools over the past 5 days. Upon admission, the patient experienced massive gastrointestinal bleeding, necessitating transfer to the intensive care unit. Colonoscopy revealed extensive ulceration with a thick gelatinous exudate and diffuse inflammation of the surrounding mucosa in the cecum and proximal ascending colon (Figure 1).

Histopathological examination of the ulcerative lesion yielded negative results for acid-fast bacilli and cytomegalovirus but revealed ulcer detritus with characteristic Kalimate crystals in the stroma (Figure 2). The crystals were polygonal and stained deep purple. The patient was confirmed to have been taking calcium polystyrene sulfonate (Kalimate) orally for more than 10 years to treat hyperkalemia. After 6 days of conservative management and Kalimate withdrawal, the hematochezia resolved spontaneously. Follow-up colonoscopy performed 2 months later showed complete healing of the ulcer (Figure 3).

Hyperkalemia is a common electrolyte imbalance that occurred in patients with ESRD. For the prevention and treatment of hyperkalemia, the prescription of cation exchange resin Kalimate or Kayexalate (sodium polystyrene sulfonate) is often necessary for ESRD patients. The incidence of colonic necrosis caused by the administration of Kalimate/Kayexalate is extremely rare, ranging from 0.14% to 1.8% [1, 2].

Due to its low rates of occurrence, promptly differentiating Kalimate-induced colitis from other causes of gastrointestinal bleeding is crucial in patients with ESRD presenting with massive hematochezia. Ischemic colitis and opportunistic infections such as cytomegalovirus colitis are the common gastrointestinal complications that should be differentially diagnosed [3]. Timely identification through immediate colonoscopy with biopsies and implementation of alternative treatments using nonabsorbable chelators can prevent further complications and improve patient outcomes.

The authors declare no conflicts of interest.