A nurse is reviewing the laboratory report of a client and identifies a serum potassium level of 6.8 mEq/L (3.5 to 5 mEq/L). Which of the following medications should the nurse plan to administer?

Choice A rationale Lactulose is a synthetic sugar used primarily to treat constipation or hepatic encephalopathy. Its mechanism of action involves drawing water into the bowel and trapping ammonia in the gut to be excreted. It has no direct effect on serum potassium levels. In a patient with a potassium level of 6.8 mEq/L, which is significantly higher than the normal range of 3.5 to 5.0 mEq/L, lactulose would provide no therapeutic benefit for hyperkalemia. Choice B rationale Sevelamer is a phosphate binder used to treat hyperphosphatemia, commonly in patients with chronic kidney disease. It works by binding to dietary phosphorus in the gastrointestinal tract, preventing its absorption. While electrolyte imbalances often occur together in renal patients, sevelamer does not lower potassium. Using it for a potassium level of 6.8 mEq/L would be inappropriate as it does not address the life-threatening risk of cardiac arrhythmias associated with such high potassium. Choice C rationale Sodium polystyrene sulfonate is a cation-exchange resin specifically indicated for the treatment of hyperkalemia. It works in the intestines by exchanging sodium ions for potassium ions, which are then excreted from the body in the feces. A serum potassium level of 6.8 mEq/L is dangerously high, as the normal range is 3.5 to 5.0 mEq/L. Administering this medication helps lower the total body potassium and prevent the severe cardiac complications associated with hyperkalemia. Choice D rationale Darbepoetin alfa is an erythropoiesis-stimulating agent used to treat anemia, particularly in patients with chronic kidney disease or those receiving chemotherapy. It works by stimulating the bone marrow to produce more red blood cells. It has no physiological role in the regulation or excretion of potassium. Therefore, it is not an appropriate intervention for a patient presenting with a serum potassium level of 6.8 mEq/L, which requires urgent potassium-lowering therapy to ensure safety.