A 45-year-old woman is evaluated in the intensive care unit on the second day of induction… — USMLE Step 2 CK

A 45-year-old woman is evaluated in the intensive care unit on the second day of induction chemotherapy for newly diagnosed high-grade Burkitt lymphoma. Over the past 8 hours, her urine output has significantly decreased. She reports mild nausea and generalized weakness. Her temperature is $37.1^\circ\text{C}$ ( $98.8^\circ\text{F}$ ), blood pressure is $110/70\text{ mmHg}$ , and pulse is $88/\text{min}$ . A stat laboratory panel shows the following results:

Laboratory Test	Result	Reference Range
Potassium	$6.8\text{ mEq/L}$	$3.5-5.0\text{ mEq/L}$
Calcium	$6.9\text{ mg/dL}$	$8.4-10.2\text{ mg/dL}$
Phosphorus	$7.8\text{ mg/dL}$	$2.5-4.5\text{ mg/dL}$
Uric acid	$14.2\text{ mg/dL}$	$2.4-6.0\text{ mg/dL}$
Creatinine	$2.6\text{ mg/dL}$	$0.6-1.1\text{ mg/dL}$

An electrocardiogram (ECG) reveals tall, peaked T waves with a shortened QT interval. Which of the following is the most appropriate next step in the management of this patient?

Administer intravenous calcium gluconateCevap
B
Administer intravenous rasburicase
C
Initiate emergency hemodialysis
D
Administer intravenous sodium bicarbonate
E
Administer broad-spectrum intravenous antibiotics

Cevap

Administer intravenous calcium gluconate

The correct answer is to administer intravenous calcium gluconate. This patient has classic Tumor Lysis Syndrome (TLS), an oncologic emergency characterized by the massive release of intracellular contents following chemotherapy. The most immediately life-threatening complication of TLS is severe hyperkalemia, which this patient has developed along with concerning ECG changes (peaked T waves). In any patient with severe hyperkalemia and associated ECG abnormalities, the absolute first step in management is to stabilize the myocardial cell membrane with intravenous calcium (gluconate or chloride) to prevent fatal ventricular arrhythmias. Once the myocardium is stabilized, subsequent therapies can be initiated to shift potassium intracellularly (e.g., insulin and glucose) and remove it from the body, alongside targeted TLS treatments like rasburicase.

Adım Adım Çözüm

Identify the underlying clinical syndrome based on the presentation and labs.

The patient has Tumor Lysis Syndrome (TLS) characterized by hyperuricemia, hyperkalemia, hyperphosphatemia, hypocalcemia, and acute kidney injury following chemotherapy for a rapidly proliferating lymphoma.

Recognizing TLS provides the necessary context for anticipating severe metabolic derangements.

Prioritize the laboratory abnormalities to identify the most immediate threat to the patient's life.

The most dangerous abnormality is the severe hyperkalemia (

6.8\text{ mEq/L}

) with corresponding ECG changes (peaked T waves).

Hyperkalemia with ECG changes indicates imminent risk of lethal ventricular arrhythmias and cardiac arrest.

Determine the most rapid and effective intervention for the primary threat.

Intravenous calcium gluconate must be administered immediately.

Calcium directly antagonizes the effects of potassium on the myocardial cell membrane, providing instant cardioprotection while other therapies to lower serum potassium and uric acid are prepared.

Anahtar Kavram

In Tumor Lysis Syndrome complicated by severe hyperkalemia with ECG changes, immediate myocardial membrane stabilization with intravenous calcium is the paramount first step in management.

Tahmini Süre:1m 15s

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