A nurse is caring for a client receiving sodium polystyrene sulfonate (Kayexalate) for the treatment of chronic renal disease. The nurse should monitor for which therapeutic effect of sodium polystyrene sulfonate (Kayexalate)?

A. Decreased urine specific gravity: Kayexalate does not affect urine concentration. Clients with chronic renal disease often produce little or no urine, so urine specific gravity is not a reliable therapeutic marker. B. Decreased serum potassium: Sodium polystyrene sulfonate is a cation-exchange resin that binds potassium in the colon and facilitates its excretion through feces. It is used to lower elevated potassium levels in clients with renal failure. C. Decreased serum sodium: Kayexalate exchanges sodium for potassium, so sodium levels may actually increase slightly. A decrease in serum sodium is not the intended or expected effect. D. Decreased serum phosphorus: Kayexalate has no effect on phosphorus levels. Phosphate binders, not potassium binders, are used to control hyperphosphatemia in chronic kidney disease.