A 58-year-old man with Burkitt lymphoma is admitted to the hospital for chemotherapy. Medical history includes hypertension, stable angina, and hyperlipidemia. Two days after starting chemotherapy, the patient reports nausea and generalized weakness. Laboratory results are as follows: ECG shows peaked T waves. In addition to calcium gluconate, which of the following is the best initial therapy for this patient?

Question

A 58-year-old man with Burkitt lymphoma is admitted to the hospital for chemotherapy.  Medical history includes hypertension, stable angina, and hyperlipidemia.  Two days after starting chemotherapy, the patient reports nausea and generalized weakness.  Laboratory results are as follows:  ECG shows peaked T waves.  In addition to calcium gluconate, which of the following is the best initial therapy for this patient?

Quizplus · Accepted Answer

This patient with Burkitt lymphoma has hyperkalemia likely due to tumor lysis syndrome from chemotherapy. Common indications for emergency treatment of hyperkalemia include hyperkalemia-related ECG changes or marked elevation (eg, >6.5 mEq/L) or rapid rise in serum potassium level. Patients with these findings have hyperkalemic emergency and are at high risk for life-threatening cardiac events such as significant bradycardia (sinus node dysfunction, atrioventricular block) and ventricular arrhythmia. ECG changes Definitive treatment of hyperkalemic emergency requires removing potassium from the body via the stool (eg, patiromer), kidneys (eg, furosemide), and/or blood (eg, hemodialysis). However, these therapies often take hours to have effect. Because hyperkalemic emergency can rapidly cause death, urgent treatment is indicated. This typically includes administering intravenous calcium (eg, calcium gluconate), which counterbalances the membrane depressive effect of hyperkalemia. In addition, intravenous insulin (often given in combination with glucose to prevent hypoglycemia) should be administered because it moves potassium into cells due to increased activity of the Na⁺/K⁺-ATPase in skeletal muscle. (Choice A) Hemodialysis is used in patients with end-stage renal disease who have severe, recalcitrant hyperkalemia. However, this therapy usually takes an hour or more to prepare (eg, catheter placement, dialysis machine setup) and is unlikely to be used in someone with mild renal failure due to tumor lysis syndrome. Calcium gluconate and insulin is required prior to considering other therapies. (Choice B) Intravenous dextrose alone would not be sufficient to move potassium into cells without insulin. (Choice C) Inhaled beta-2 agonists shift potassium intracellularly due to stimulation of the Na⁺/K⁺-ATPase, but this class of medications is generally considered 3^rd line for hyperkalemia behind intravenous calcium and insulin plus glucose. Beta-2 agonists are generally avoided in patients with active coronary artery disease (as in this patient with stable angina) due to risk of tachycardia-induced angina. ^rd (Choice E) Furosemide promotes renal potassium excretion, but it does not generally take effect for >30 minutes. This patient with peaked T waves requires urgent stabilization of the cardiac membrane with intravenous calcium and lowering of serum potassium with insulin prior to consideration of other therapies. (Choice F) Intravenous sodium bicarbonate alkalinizes the blood, which shifts intracellular hydrogen into the extracellular space. This creates an electrochemical gradient that pulls potassium into cells. However, sodium bicarbonate has little effect alone and is not regularly recommended as first- or second-line therapy. Educational objective: Hyperkalemic emergency is marked by ECG changes, cardiac arrhythmia, and/or sudden or dramatic rise in serum potassium. Urgent treatment with calcium gluconate to stabilize the cardiac membrane and insulin plus glucose to shift serum potassium into cells is indicated. Definitive removal of potassium via the stool (eg, patiromer), kidneys (eg, furosemide), and/or blood (eg, hemodialysis) should then be initiated.

A 58-Year-Old Man with Burkitt Lymphoma Is Admitted to the Hospital