A 52-year-old man is hospitalized to undergo induction chemotherapy for newly diagnosed Burkitt lymphoma. Twenty-four hours after the initiation of the cytotoxic regimen, he reports new-onset muscle cramps, palpitations, and nausea. His temperature is 37.2°C (99.0°F), pulse is 108/min, and blood pressure is 110/70 mm Hg. Physical examination reveals normal heart sounds and clear lungs.
Laboratory studies show the following:
| Test | Result | Reference Range |
|---|---|---|
| Potassium | 6.8 mEq/L | 3.5-5.0 mEq/L |
| Creatinine | 2.8 mg/dL | 0.7-1.3 mg/dL |
| Calcium | 6.8 mg/dL | 8.4-10.2 mg/dL |
| Phosphorus | 8.5 mg/dL | 2.5-4.5 mg/dL |
| Uric acid | 14.2 mg/dL | 3.5-7.2 mg/dL |
An electrocardiogram (ECG) reveals peaked T waves and a shortened QT interval. The patient is currently receiving aggressive intravenous normal saline and allopurinol. Which of the following is the most appropriate next step in management?
- AIntravenous rasburicase
- BUrgent hemodialysis
- COral sevelamer
- Intravenous calcium gluconateCevap
- EIntravenous insulin and glucose
Cevap
Intravenous calcium gluconate
This patient is experiencing tumor lysis syndrome (TLS), an oncologic emergency caused by the massive release of intracellular contents following cytotoxic therapy for rapidly proliferating tumors, such as Burkitt lymphoma. This massive cell death results in hyperkalemia, hyperphosphatemia, hypocalcemia, and hyperuricemia. The most immediate and critical life-threatening complication of TLS is severe hyperkalemia, which can trigger fatal cardiac arrhythmias (e.g., ventricular fibrillation). This patient has a critically elevated potassium level of 6.8 mEq/L and peaked T waves on his ECG, indicating active myocardial toxicity. The absolute most appropriate initial step in management is the administration of intravenous calcium gluconate (or calcium chloride). Calcium directly antagonizes the depolarization effects of hyperkalemia by raising the threshold potential, thereby stabilizing the cardiac myocyte membrane. It works within minutes, buying crucial time to implement additional therapies that actually remove potassium from the body.
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Anahtar Kavram
In patients with tumor lysis syndrome presenting with severe hyperkalemia and ECG changes, the immediate administration of intravenous calcium gluconate is the most critical next step to stabilize the cardiac membrane and prevent fatal arrhythmias.