Anatomic Pathology: Gastrointestinal Pathology

174) A 71-year-old woman with a history of chronic renal failure presented with lower gastrointestinal bleeding. Colonoscopy showed patchy mucosal ulceration. The following statements are true regarding the findings in this case EXCEPT:

• Kayexalate is a powdered form of sodium polysterene sulphonate that is usually suspended in sorbitol and given for the treatment of hyperkalemia in patients with renal insufficiency. In some cases administration of kayexalate in sorbitol can cause significant gastrointestinal damage, including life threatening intestinal necrosis. The incidence of this is not well established, but is estimated to be less than 2%.

• The degree of gastrointestinal damage seen with kayexalate in sorbitol varies. In the lower GI tract histopathologic findings include mucosal ulcers, pseudomembranes, edema, mucosal or transmural necrosis, and perforation. The latter can be life threatening and require surgical intervention.

• In the upper gastrointestinal tract, administration of kayexalate in sorbitol can result in erosions or ulcers in the esophagus and stomach. It has not been reported to cause life threatening complications.

• The exact mechanism by which administration of kayexalate in sorbitol cause damage is not known. Sorbitol is believed to be the agent responsible for the damage, as experiments in rats showed no damage to the gastrointestinal tract following administration of sorbitol alone or kayexalate in sorbitol, but not following administration of kayexalate in saline. Sorbitol is a poorly absorbed sugar that acts as an osmotic laxative and it is thought that in susceptible patients the osmotic load might cause vascular shunting and intestinal ischemia. Patients with more severe hypovolemia and hypotension are at higher risk for developing gastrointestinal complications.

• Deposition of kayexalate crystals can be an incidental finding in the absence of gastrointestinal injury. In addition, patients treated with kayexalate in sorbitol may have other conditions, such as infections, that might be causing the observed injury. It is important though to recognize the presence of kayexalate crystals in biopsy or resection specimens, and discuss the case with the clinician.

* = Required 
* Note Title
* Note