A 45-year-old man is admitted to the intensive care unit for initiation of induction chemo… — USMLE Step 3

A 45-year-old man is admitted to the intensive care unit for initiation of induction chemotherapy for newly diagnosed Burkitt lymphoma. He has a massive retroperitoneal tumor burden and baseline renal impairment with a serum creatinine of $1.8 \text{ mg/dL}$ . Recognizing his high risk for tumor lysis syndrome (TLS), the medical team initiates aggressive intravenous hydration and administers a dose of rasburicase prior to starting the chemotherapy regimen.

Twelve hours after the initiation of chemotherapy, the patient is noted to be oliguric, with a urine output of only $20 \text{ mL/hr}$ over the last 6 hours. Continuous telemetric monitoring reveals new-onset peaked T waves.

Stat laboratory studies are obtained:

Laboratory Parameter	Value	Reference Range
Potassium	$6.8 \text{ mEq/L}$	$3.5-5.0 \text{ mEq/L}$
Phosphorus	$8.5 \text{ mg/dL}$	$2.5-4.5 \text{ mg/dL}$
Calcium (total)	$6.4 \text{ mg/dL}$	$8.4-10.2 \text{ mg/dL}$
Uric acid	$2.5 \text{ mg/dL}$	$3.0-8.0 \text{ mg/dL}$
Creatinine	$3.2 \text{ mg/dL}$	$0.7-1.3 \text{ mg/dL}$

Based on the patient's monitoring data, which of the following are the most appropriate NEXT STEPS in the treatment evaluation and management of this patient? (Select the 2 correct answers)

Administer intravenous calcium gluconateCevap
Consult nephrology for emergent renal replacement therapyCevap
C
Administer a continuous infusion of sodium bicarbonate for urine alkalinization
D
Administer an additional dose of intravenous rasburicase
E
Administer oral sevelamer to acutely lower serum phosphorus
F
Administer high-volume intravenous normal saline at 250 mL/hr to force diuresis

Cevap

The correct next steps are to administer intravenous calcium gluconate and consult nephrology for emergent renal replacement therapy.

The correct next steps address two simultaneous, life-threatening emergencies. First, the patient has severe hyperkalemia with peaked T waves on telemetry. While standard tumor lysis syndrome (TLS) protocols dictate avoiding calcium administration for asymptomatic hypocalcemia (to prevent widespread calcium-phosphate tissue precipitation), the presence of hyperkalemic electrocardiographic changes makes cardioprotection with intravenous calcium gluconate an immediate, absolute necessity. Second, the patient has oliguric acute kidney injury with massive potassium and phosphorus release that cannot be managed medically. Emergent renal replacement therapy (hemodialysis) is definitively required to rapidly clear these electrolytes and manage volume status.

Adım Adım Çözüm

Interpret continuous telemetry and serial laboratory data.

Identifies severe hyperkalemia (

6.8 \text{ mEq/L}

) with ECG changes (peaked T waves), severe hyperphosphatemia, profound hypocalcemia, and oliguric acute kidney injury.

Accurate interpretation of post-chemotherapy monitoring is required to establish emergency management priorities.

Stabilize the cardiac membrane.

Administer intravenous calcium gluconate.

Although calcium administration is generally avoided in TLS-associated hypocalcemia to prevent calcium-phosphate precipitation, the presence of hyperkalemia with electrocardiographic changes makes cardioprotection an absolute priority to prevent fatal arrhythmias.

Address severe oliguric acute kidney injury and electrolyte derangements.

Consult nephrology for emergent hemodialysis.

Medical management is insufficient for clearing massive potassium and phosphorus loads in the setting of oliguric renal failure; renal replacement therapy is definitively required.

Anahtar Kavram

In Tumor Lysis Syndrome, asymptomatic hypocalcemia should not be treated with calcium due to precipitation risks; however, if hyperkalemia with ECG changes occurs, IV calcium gluconate is mandatorily indicated for cardioprotection alongside emergent hemodialysis.

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Cevap

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