A 52-year-old man is hospitalized for the treatment of newly diagnosed Burkitt lymphoma. Twenty-four hours after receiving his first dose of systemic chemotherapy, he reports weakness, severe muscle cramps, and nausea. His temperature is 37.2°C (99.0°F), blood pressure is 110/70 mm Hg, pulse is 105/min, and respirations are 16/min.
Laboratory studies show:
| Test | Result |
|---|---|
| Sodium | 138 mEq/L |
| Potassium | 7.1 mEq/L |
| Bicarbonate | 18 mEq/L |
| Blood urea nitrogen | 42 mg/dL |
| Creatinine | 2.6 mg/dL (baseline 0.8 mg/dL) |
| Calcium | 6.8 mg/dL |
| Phosphorus | 8.5 mg/dL |
| Uric acid | 15.2 mg/dL |
An electrocardiogram reveals peaked T waves and a prolonged PR interval. Which of the following is the most appropriate immediate next step in management?
- Intravenous calcium gluconateAnswer
- BIntravenous regular insulin and dextrose
- CIntravenous rasburicase
- DContinuous renal replacement therapy
- EIntravenous normal saline bolus
Answer
Intravenous calcium gluconate
The correct answer is intravenous calcium gluconate. This patient's presentation of hyperkalemia, hyperphosphatemia, hypocalcemia, and hyperuricemia following chemotherapy for a high-grade malignancy (Burkitt lymphoma) is the classic presentation of tumor lysis syndrome (TLS). The massive release of intracellular contents leads to significant metabolic derangements. The most immediate life-threatening complication is severe hyperkalemia, which can trigger fatal cardiac arrhythmias. The presence of peaked T waves and a prolonged PR interval confirms clinically significant cardiac toxicity. The absolute first step in managing hyperkalemia with electrocardiographic changes is to stabilize the myocardial membrane with intravenous calcium (gluconate or chloride), which works within minutes. Only after calcium is given should therapies be administered to drive potassium intracellularly (e.g., insulin and dextrose) or remove it from the body.
Step-by-Step Solution
Key Concept
In tumor lysis syndrome, the most immediate life-threatening complication is hyperkalemia. When hyperkalemia is accompanied by electrocardiographic changes, the absolute first step in management is myocardial stabilization with intravenous calcium.