Kayexalate (Sodium Polystyrene Sulfonate) as a Hallmark and Cause of Gastrointestinal Tract Injury: Two Case Reports and a Review of the Literature

Kayexalate (sodium polystyrene sulfonate) is a cation exchange resin that is commonly used for the treatment for hyperkalemia. With the increasing prevalence of type II diabetes mellitus in developed nations, there has been a concordant rise in renal disease and hyperkalemic patients receiving Kayexalate therapy. Gastrointestinal necrosis is a rare but major complication associated with Kayexalate use that has not been previously well characterized in the forensic literature. Kayexalate crystals have a distinctive “mosaic” appearance on hematoxylin and eosin stained sections and a characteristic coloration with periodic acid-Schiff (PAS) and acid-fast stains. As they are relatively easily identified in histologic sections, and may represent a primary or contributory cause of death, it is suggested that forensic pathologists become familiar with these features. We present two cases in which Kayexalate crystals were detected at autopsy. In one case, the crystals were located within the intestinal lumen and mucosa in areas of mucosal ulceration, while in the other, crystals were located on the intestinal serosal surface without apparent mucosal ulceration. We discuss how to interpret the significance of Kayexalate crystals, review prior literature on Kayexalate therapy-related gastrointestinal necrosis, and explain how to notify the Food and Drug Administration of an adverse Kayexalate reaction detected at autopsy.