In a patient with diffuse large B‑cell/Burkitt lymphoma receiving B‑CHOP chemotherapy who presents with hyperkalemia, hypocalcemia and oliguria/anuria, what is the most appropriate management in addition to aggressive intravenous hydration?

Rasburicase is the Most Appropriate Management

In a patient with DLBCL/Burkitt lymphoma receiving B-CHOP chemotherapy who presents with hyperkalemia (6 mmol/L), hypocalcemia, and anuria, rasburicase 0.2 mg/kg IV over 30 minutes should be administered immediately in addition to aggressive hydration. 1, 2

Clinical Diagnosis: Tumor Lysis Syndrome

This patient meets criteria for clinical tumor lysis syndrome (TLS), defined by the presence of at least 2 metabolic abnormalities (hyperkalemia and hypocalcemia) plus acute kidney injury (anuria). 1, 2 The European Hematology Association and American Society of Hematology strongly recommend rasburicase for all patients with clinical TLS, regardless of whether uric acid levels have been measured or documented. 1, 3

Why Rasburicase is Superior

• Rasburicase enzymatically converts existing uric acid to allantoin, which is 5–10 times more soluble than uric acid, providing immediate reduction of the metabolic burden even in anuric patients. 1, 2

• In randomized trials of high-risk hematologic malignancies, rasburicase achieved mean uric acid area-under-curve of 128 ± 70 mg·dL⁻¹·h versus 329 ± 129 mg·dL⁻¹·h with allopurinol (p < 0.001). 1, 4

• Even in complete renal shutdown, rasburicase reduces metabolic burden and may facilitate earlier renal recovery once dialysis is initiated. 2

• Rasburicase produces a 97–100% response rate for uric acid control, with normalization within 4 hours of the first dose. 2, 5

Why Loop Diuretics (Lasix) Are Contraindicated

• Loop diuretics are absolutely contraindicated in established anuria despite adequate hydration because they require residual renal tubular function to work. 1, 2

• Guidelines explicitly state that loop diuretics should only be used to maintain urine output ≥100 mL/hour in patients who are still producing urine after adequate volume resuscitation—not in anuric patients. 1, 2

• In this anuric patient, furosemide would be ineffective and potentially harmful by delaying definitive therapy. 1, 2

Why Thiazide Diuretics Are Incorrect

• Thiazide diuretics have no role in TLS management and are not mentioned in any TLS guideline. 1

• Thiazides are contraindicated in TLS because they decrease uric acid excretion, potentially worsening hyperuricemia and precipitating uric acid nephropathy. 2

• Thiazides are ineffective when renal function is severely impaired or absent. 1

Complete Management Algorithm

Immediate Interventions (First 30 Minutes)

• Administer rasburicase 0.2 mg/kg IV over 30 minutes through central venous access if available. 1, 2

• Continue aggressive IV hydration at 150–200 mL/hour (approximately 4–5 L/m²/day) to achieve target urine output ≥100 mL/hour if renal function recovers. 1, 2

• Initiate continuous ECG monitoring for hyperkalemia-induced arrhythmias. 1, 2

Hyperkalemia Management (K = 6 mmol/L)

• Calcium gluconate 50–100 mg/kg IV over 2–5 minutes to stabilize cardiac membranes. 1, 2

• Rapid insulin 0.1 units/kg IV plus 25% dextrose 2 mL/kg IV to shift potassium intracellularly. 1, 2

• Sodium polystyrene sulfonate 1 g/kg orally or by enema for ongoing potassium removal. 1, 2

• Sodium bicarbonate if metabolic acidosis is present. 1

Hypocalcemia Management

• Do NOT treat asymptomatic hypocalcemia beyond the initial calcium gluconate dose used for cardiac membrane stabilization, as calcium administration can precipitate calcium-phosphate crystals and worsen renal injury. 1, 2

• Only treat hypocalcemia if the patient develops tetany, seizures, or prolonged QT interval. 1, 2

Urgent Nephrology Consultation

• Contact nephrology immediately for hemodialysis when anuria persists despite aggressive hydration. 1, 2

• The combination of anuria plus hyperkalemia ≥6 mmol/L constitutes an absolute indication for emergent dialysis. 1, 2

• Hemodialysis can lower plasma uric acid by approximately 50% with each 6-hour session while simultaneously correcting life-threatening hyperkalemia. 1, 2

Monitoring Requirements

• Hourly urine output targeting ≥100 mL/hour. 1, 2

• Electrolytes, uric acid, phosphate, calcium, and creatinine every 4–6 hours for the first 24 hours. 1, 2

• Continuous ECG monitoring for arrhythmias. 1, 2

Critical Pitfall to Avoid

Never delay rasburicase administration while waiting for uric acid levels to return from the laboratory. 3 The European Hematology Association explicitly states that rasburicase should be given to all patients with clinical TLS even when uric acid levels are not documented, because TLS is defined by the presence of at least 2 metabolic abnormalities—not necessarily hyperuricemia. 3

G6PD Screening Consideration

• Prior to rasburicase administration, patients at risk for glucose-6-phosphate dehydrogenase (G6PD) deficiency (African or Mediterranean ancestry) should ideally be screened, as rasburicase is absolutely contraindicated in G6PD-deficient individuals due to severe hemolysis risk. 1, 3

• However, in life-threatening TLS with anuria and severe hyperkalemia, do not delay rasburicase if G6PD status is unknown and results cannot be obtained rapidly. 3