In a patient with diffuse large B‑cell lymphoma receiving B‑CHOP chemotherapy who now has hyperkalemia, hypocalcemia, hyperphosphatemia and oliguria, what is the most appropriate management in addition to aggressive IV hydration?

Management of Tumor Lysis Syndrome with Oliguria in DLBCL

This patient requires immediate rasburicase administration, aggressive management of hyperkalemia, and urgent preparation for hemodialysis given the triad of oliguria, severe hyperkalemia (K=6), and laboratory tumor lysis syndrome. 1

Clinical Recognition

This presentation is pathognomonic for tumor lysis syndrome (TLS) in a lymphoma patient receiving chemotherapy, characterized by:

• Hyperkalemia (6 mmol/L) from massive intracellular potassium release 2, 1
• Hypocalcemia resulting from calcium-phosphate precipitation 1
• Hyperphosphatemia from intracellular phosphate release 2, 1
• Oliguria/anuria indicating acute kidney injury—a medical emergency 1

The inability to urinate represents critical renal failure and mandates the most aggressive intervention available. 1

Immediate Management: Rasburicase (Answer C)

Rasburicase is the correct answer because:

• Rasburicase prophylaxis is specifically recommended for patients with oliguria and evidence of renal insufficiency 1
• Even without documented hyperuricemia mentioned in the question, rasburicase rapidly degrades uric acid and prevents further renal damage from uric acid crystallization 2, 3
• Hydration and rasburicase should be administered to all patients with clinical TLS (which includes oliguria/anuria) 2
• Rasburicase achieves uric acid control within 4 hours in 98% of adult patients 3

Why the Other Options Are Wrong

A. Lasix (Loop Diuretics) - Fundamentally contraindicated: Loop diuretics in oliguric patients represent a fundamental misunderstanding of acute kidney injury management 1. While loop diuretics may be used to maintain urine output in non-oliguric patients (≥100 mL/hour), they are explicitly contraindicated in established oliguria/anuria and with concomitant obstructive uropathy or hypovolemia 2.

B. Thiazide Diuretics - No role whatsoever in TLS management and would worsen electrolyte abnormalities 2.

D. Prednisone - While corticosteroid prephase (prednisone 100 mg daily for 5-7 days) is recommended before initiating chemotherapy in high tumor burden patients to prevent TLS 1, 4, 5, it has no role in treating established TLS with oliguria and life-threatening hyperkalemia. The patient is already receiving prednisone as part of the B-CHOP regimen.

Comprehensive TLS Management Algorithm

Step 1: Immediate Interventions (First Hour)

• Rasburicase 0.15-0.20 mg/kg IV as a single dose 2, 3
• Aggressive IV hydration at 2-3 L/m²/day to maintain urine output ≥100 mL/m²/hour (if urine output returns) 2, 1
• Urgent nephrology consultation for hemodialysis preparation 1

Step 2: Hyperkalemia Management (Concurrent)

For severe hyperkalemia (K=6 mmol/L):

• Calcium gluconate 50-100 mg/kg IV to stabilize myocardial membrane 2
• Insulin 0.1 units/kg + 25% dextrose 2 mL/kg IV for rapid intracellular potassium shift 2
• Sodium polystyrene sulfonate 1 g/kg orally or by enema 2
• Continuous ECG monitoring for arrhythmias 2
• Avoid potassium intake completely 6

Step 3: Dialysis Indications

Do not delay dialysis if: 1

• Hyperkalemia is life-threatening (K ≥6.5 or ECG changes)
• Oliguria persists despite initial management
• Severe hyperphosphatemia with symptomatic hypocalcemia
• Volume overload from aggressive hydration

Step 4: Additional Supportive Measures

• Hypocalcemia: Only treat if symptomatic (tetany, seizures) with calcium gluconate 50-100 mg/kg as a single cautious dose 2. Asymptomatic hypocalcemia does not require treatment 2.
• Hyperphosphatemia: Mild cases (<1.62 mmol/L) can be treated with aluminum hydroxide 50-100 mg/kg/day divided in 4 doses 2
• Avoid urinary alkalinization—no longer recommended in TLS management 1

Critical Pitfalls to Avoid

• Never use loop diuretics in oliguric/anuric patients—this worsens outcomes and delays appropriate dialysis 1
• Never delay dialysis when hyperkalemia is life-threatening or oliguria persists 1
• Never treat asymptomatic hypocalcemia aggressively—calcium administration with hyperphosphatemia can cause metastatic calcification 2
• Never withhold rasburicase based on absence of documented hyperuricemia—the drug prevents further uric acid generation and renal damage 2, 1

Prognosis and Monitoring

• Rasburicase decreases plasma uric acid within 4 hours and maintains levels <7.5 mg/dL in 98% of patients 3
• Terminal half-life is 15.7-22.5 hours with minimal accumulation 3
• Despite aggressive management, mortality remains significant in TLS with established renal failure, as demonstrated in case reports where patients progressed to multiorgan failure 7, 6
• Close monitoring of electrolytes and renal function every 4-6 hours is mandatory during the acute phase 1