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

Management of Tumor Lysis Syndrome with Anuria

This patient requires immediate rasburicase administration and urgent hemodialysis—neither furosemide (Lasix) nor thiazides have any role in an anuric patient, and attempting diuresis in this setting wastes critical time and delays life-saving treatment. 1, 2

Clinical Recognition

This patient has clinical tumor lysis syndrome (TLS) with anuria, which is a medical emergency requiring immediate intervention to prevent death from cardiac arrhythmias and progressive multi-organ failure. 1, 2, 3

• The constellation of hyperkalemia and hypocalcemia in a lymphoma patient receiving chemotherapy defines at least 2 of the 4 biochemical abnormalities characteristic of TLS (hyperkalemia, hyperphosphatemia, hypocalcemia, hyperuricemia). 1, 2
• The inability to urinate indicates progression to clinical TLS with acute oliguric renal failure, likely from uric acid crystallization in the collecting ducts and renal vessels. 1

Immediate Management Algorithm

Step 1: Rasburicase Administration (Answer: C)

Rasburicase must be administered immediately to all patients with clinical TLS, regardless of whether uric acid levels are available. 1, 2, 3

• Rasburicase rapidly degrades uric acid within hours, preventing further renal damage from uric acid crystallization and allowing potential recovery of renal function. 1, 2
• The drug works so rapidly that mean serum uric acid decreases from 15.1 to 0.4 mg/dL in hyperuricemic patients, with 100% response rates in clinical trials. 1, 2
• Do not delay rasburicase while waiting for uric acid levels—the clinical picture of TLS is sufficient indication. 2, 3

Step 2: Urgent Hemodialysis

Hemodialysis must be initiated urgently for this anuric patient with severe TLS. 1, 2, 3

• Hemodialysis is the only definitive treatment that removes potassium from the body in an anuric patient, with uric acid clearance of approximately 70-100 mL/min. 1, 2
• Plasma uric acid falls by about 50% with each 6-hour hemodialysis treatment, and oliguria due to acute uric acid nephropathy often responds rapidly once plasma uric acid falls to 10 mg/dL. 1
• Early initiation of renal replacement therapy removes purine by-products and corrects hyperkalemia, hyperphosphatemia, and hypocalcemia. 1, 3

Step 3: Temporizing Measures for Hyperkalemia

While arranging urgent dialysis, administer the following to stabilize the patient:

• Insulin 0.1 units/kg IV plus 25% dextrose 2 mL/kg to shift potassium intracellularly (onset 15-30 minutes, duration 4-6 hours). 1, 3
• Calcium gluconate 50-100 mg/kg IV to stabilize the myocardial cell membrane (effects within 1-3 minutes but lasting only 30-60 minutes). 1, 3
• Sodium bicarbonate to correct acidosis and stabilize cardiac membranes. 1
• Continuous ECG monitoring throughout acute management. 1, 2

Step 4: Management of Hypocalcemia

• Asymptomatic hypocalcemia does not require treatment. 1, 2
• If symptoms develop (tetany, seizures), administer calcium gluconate 50-100 mg/kg as a single dose, repeated cautiously if necessary. 1, 2

Critical Pitfalls to Avoid

Never attempt diuresis with furosemide (Lasix) or thiazides in an anuric patient—this is futile and dangerous, wasting precious time while the patient deteriorates. 1, 2

• Loop diuretics are only indicated to maintain urine output (≥100 mL/hour) in patients who still have renal function, and are specifically contraindicated in patients with obstructive uropathy or hypovolemia. 1, 3
• In an anuric patient, diuretics cannot work because there is no functioning nephron to act upon. 2, 3

Remember that calcium, insulin, and beta-agonists only temporize hyperkalemia—they shift potassium intracellularly but do not remove it from the body. 2, 4, 5

Verify G6PD status before rasburicase administration—the drug is contraindicated in G6PD-deficient patients. 2

Monitoring Protocol

• Recheck potassium, calcium, phosphate, and uric acid every 2-4 hours initially. 2, 3, 6
• Continue ECG monitoring throughout acute management. 1, 2
• Monitor urine output closely once diuresis resumes after dialysis. 2, 3