In a patient with Burkitt lymphoma receiving B‑CHOP chemotherapy who is anuric with hyperkalemia and hypocalcemia, what is the most appropriate management in addition to aggressive hydration?

Management of Tumor Lysis Syndrome with Anuria and Severe Hyperkalemia

In this anuric patient with Burkitt lymphoma presenting with clinical tumor lysis syndrome (hyperkalemia 6 mmol/L, hypocalcemia, anuria), rasburicase is the most appropriate management in addition to aggressive hydration, as loop diuretics are contraindicated in established anuria and this patient requires urgent dialysis. 1, 2

Why Rasburicase is the Correct Answer

Rasburicase must be administered immediately at 0.2 mg/kg IV over 30 minutes to all patients with clinical TLS, which this patient clearly has (anuria represents acute kidney injury, a defining feature of clinical TLS). 3, 2 The rapid degradation of uric acid by rasburicase can help prevent complete renal shutdown and potentially restore some renal function, even though this patient will likely still require dialysis. 2

• Rasburicase works by directly converting uric acid to allantoin (a more soluble metabolite), achieving uric acid clearance far more rapidly than any diuretic could accomplish 3
• The European Society for Medical Oncology and American Society of Hematology both mandate rasburicase administration through central venous access for all patients with clinical TLS 3, 1, 2
• Even in anuric patients, rasburicase reduces the metabolic burden and may facilitate earlier recovery of renal function once dialysis is initiated 3

Why Loop Diuretics (Lasix/Furosemide) Are Incorrect

Loop diuretics are absolutely contraindicated in patients with established anuria despite adequate hydration. 1, 2 This is a critical pitfall to avoid:

• The American College of Cardiology explicitly advises against using loop diuretics in patients with anuria or established oliguria despite adequate hydration 1
• Loop diuretics only work when there is residual renal function to augment—they cannot restore urine output in complete renal shutdown 3, 1
• This patient is "unable to urinate" (anuric), meaning furosemide will provide no benefit and may delay appropriate escalation to dialysis 1, 2
• Loop diuretics are appropriate only for maintaining urine output ≥100 mL/hour in patients who still have some urine production after adequate volume resuscitation 3, 1

Why Thiazide Diuretics Are Incorrect and Dangerous

Thiazide diuretics are contraindicated in tumor lysis syndrome because they decrease uric acid excretion, potentially worsening hyperuricemia and precipitating uric acid nephropathy. 1 This would be catastrophic in a patient already in acute renal failure from TLS.

• Thiazides reduce renal uric acid clearance, directly opposing the therapeutic goal in TLS 1
• The research evidence on thiazide-loop diuretic combinations applies only to heart failure with preserved renal function, not to anuric TLS patients 4, 5

Complete Management Algorithm for This Patient

Immediate Actions (Within Minutes)

1. Administer rasburicase 0.2 mg/kg IV over 30 minutes immediately 2
2. Give calcium gluconate 50-100 mg/kg IV over 2-5 minutes to stabilize the myocardial membrane given severe hyperkalemia (6 mmol/L) 1, 2
3. Administer rapid insulin 0.1 units/kg IV plus 25% dextrose 2 mL/kg IV to acutely lower potassium (onset 15-30 minutes, duration 4-6 hours) 1, 2
4. Initiate continuous ECG monitoring for hyperkalemia-induced arrhythmias 3, 1

Urgent Consultation (Within 1-2 Hours)

Contact nephrology immediately for urgent hemodialysis. 3, 1, 2 The American Society of Nephrology recommends initiating hemodialysis urgently when:

• Oliguria or anuria develops despite aggressive hydration (this patient is anuric) 1, 2
• Severe refractory hyperkalemia ≥6 mmol/L unresponsive to medical management 2
• The combination of anuria plus hyperkalemia 6 mmol/L is an absolute indication for emergent dialysis 3, 1

Ongoing Management

• Continue aggressive IV hydration through central venous access (150-200 mL/hour or 3.5-4.5 L/day), though recognize this patient may develop volume overload given anuria 1
• Recheck potassium every 2-4 hours after initial treatment 1, 2
• Monitor uric acid, electrolytes, phosphate, and calcium every 6 hours for the first 24 hours 1
• Do NOT treat asymptomatic hypocalcemia beyond the initial calcium gluconate for cardiac membrane stabilization, as calcium administration can precipitate calcium-phosphate crystals and worsen renal injury 3, 1

Critical Pitfall to Avoid

The most dangerous error would be administering furosemide to an anuric patient, delaying recognition that urgent dialysis is needed. 1, 2 Anuria in TLS represents acute uric acid nephropathy with possible calcium-phosphate precipitation in renal tubules—this requires dialysis, not diuretics. 3 Hemodialysis achieves uric acid clearance of 70-100 mL/min and can reduce plasma uric acid by 50% with each 6-hour treatment, while simultaneously correcting life-threatening hyperkalemia. 3