What is the most appropriate management for a patient with lymphoma receiving B-Cell Chemotherapy (B-CHOP) with hyperkalemia, hypocalcemia, and acute kidney injury, who is unable to urinate?

Management of Tumor Lysis Syndrome with Anuria

The most appropriate management is C. Rasburicase, as this patient has clinical tumor lysis syndrome with anuria, which requires immediate rasburicase administration along with urgent preparation for hemodialysis. 1, 2

Why Rasburicase is the Correct Answer

Rasburicase should be administered immediately to all patients with clinical TLS, defined by at least 2 biochemical abnormalities (hyperkalemia and hypocalcemia in this case) plus clinical complications such as renal failure/anuria. 3, 1, 2

• Rasburicase 0.2 mg/kg IV over 30 minutes works within hours to rapidly degrade uric acid to allantoin, preventing further renal damage from uric acid crystallization 1, 4
• In hyperuricemic patients, mean serum uric acid decreased from 15.1 to 0.4 mg/dL with rasburicase treatment 3, 2
• Plasma uric acid levels reach ≤2 mg/dL in 96% of patients within 4 hours of the first dose 4

Why Loop Diuretics (Lasix) Are Contraindicated

Guidelines explicitly state that loop diuretics should NOT be used in patients with anuria or oliguria despite adequate hydration. 1, 2

• Attempting diuresis with furosemide in an anuric patient wastes critical time and delays appropriate treatment 2
• Loop diuretics are only appropriate when urine output needs to be maintained at ≥100 mL/hour in patients who are still producing urine, and only after adequate hydration has been established 3, 5

Why Thiazides Are Not Appropriate

• Thiazide diuretics have no role in the acute management of tumor lysis syndrome 1, 2
• Like loop diuretics, they cannot work in an anuric patient and would delay definitive treatment 1

Additional Critical Management Steps

Immediate Hyperkalemia Management

• For severe hyperkalemia (≥6 mmol/L or any ECG changes): administer calcium gluconate 50-100 mg/kg IV over 2-5 minutes to stabilize myocardial membrane 3, 1
• Give insulin 0.1 units/kg IV plus 25% dextrose 2 mL/kg IV to shift potassium intracellularly 3, 1, 2
• Consider sodium polystyrene sulfonate 1 g/kg orally or by enema for additional potassium removal 3, 1
• Continuous ECG monitoring is mandatory for arrhythmia detection 3, 1, 2

Hypocalcemia Management

Do NOT treat asymptomatic hypocalcemia in TLS. 1, 2

• Only administer calcium gluconate 50-100 mg/kg IV if the patient develops tetany, seizures, or prolonged QT interval 3, 1, 2
• Never give calcium in the presence of hyperphosphatemia unless symptomatic, as this causes metastatic calcification and worsens renal function 1

Urgent Hemodialysis Preparation

The American Society of Nephrology recommends initiating hemodialysis urgently when anuria develops despite aggressive hydration. 1

• Hemodialysis is the most effective method for removing potassium and provides uric acid clearance of approximately 70-100 mL/min 2
• Never delay dialysis in anuric patients—waiting for medical management increases mortality risk from hyperkalemia-induced cardiac arrest 1
• Remember that calcium, insulin, and other temporizing measures do not remove potassium from the body; they only redistribute it temporarily 2

Critical Monitoring Parameters

• Recheck potassium, calcium, phosphate, and uric acid every 2-4 hours initially 1, 2
• Obtain comprehensive metabolic panel every 4-6 hours 1
• Continue continuous ECG monitoring throughout acute management 3, 1, 2
• Monitor urine output hourly once diuresis resumes 1, 2

Important Contraindication

Verify G6PD status before rasburicase administration—the drug is absolutely contraindicated in G6PD-deficient patients due to risk of severe hemolysis and methemoglobinemia. 2, 4, 6