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

Management of Tumor Lysis Syndrome with Anuria

This patient requires immediate rasburicase administration and urgent hemodialysis—loop diuretics like Lasix are contraindicated in anuria, and thiazide diuretics worsen hyperuricemia and are never appropriate in tumor lysis syndrome. 1, 2

Immediate Management Algorithm

First-Line Treatment: Rasburicase

• Administer rasburicase 0.2 mg/kg IV over 30 minutes immediately 2, 3, 4
• Rasburicase is mandatory for all patients with clinical TLS (defined as ≥2 metabolic abnormalities plus clinical complications such as renal failure/anuria) 1, 5
• This rapidly degrades existing uric acid to allantoin within 4 hours, with 96% of patients achieving uric acid ≤2 mg/dL by 4 hours 4
• Continue daily dosing for 3-5 days as needed based on uric acid levels 3

Second-Line Treatment: Urgent Hemodialysis

• Initiate hemodialysis immediately for anuria despite adequate hydration 1, 5, 2, 3
• Hemodialysis effectively removes uric acid (clearance 70-100 mL/min), phosphate, and potassium while managing volume overload 1
• Oliguria/anuria due to acute uric acid nephropathy typically responds rapidly to hemodialysis, often restarting diuresis as plasma uric acid falls to 10 mg/dL 1

Management of Severe Hyperkalemia

Since this patient has hyperkalemia and is unable to urinate, assume severe hyperkalemia (≥6 mmol/L) until proven otherwise:

• Calcium gluconate 50-100 mg/kg IV over 2-5 minutes to stabilize myocardial membrane (onset immediate, duration 30-60 minutes) 1, 5, 2, 3
• Insulin 0.1 units/kg IV plus 25% dextrose 2 mL/kg IV to shift potassium intracellularly (onset 15-30 minutes, duration 4-6 hours) 1, 5, 2, 3
• Continuous ECG monitoring for arrhythmias 1, 5
• Sodium polystyrene sulfonate 1 g/kg orally or by enema for adjunctive potassium removal 1

Management of Hypocalcemia

• Do NOT treat asymptomatic hypocalcemia 1, 5, 2
• Calcium administration in the presence of hyperphosphatemia causes metastatic calcium-phosphate precipitation in tissues and worsens renal injury 5, 2
• Only treat if symptomatic (tetany, seizures, prolonged QT): calcium gluconate 50-100 mg/kg IV cautiously 1, 5, 2

Why the Other Options Are Wrong

Lasix (Loop Diuretics) - CONTRAINDICATED

• Loop diuretics are explicitly contraindicated in patients with anuria or established oliguria despite adequate hydration 1, 5, 2
• Guidelines state loop diuretics may be used ONLY to maintain urine output in patients who are adequately hydrated and still producing urine—not to restart urine production 1
• In anuric patients, loop diuretics provide no benefit and delay definitive treatment with dialysis 2

Thiazide Diuretics - CONTRAINDICATED

• Thiazide diuretics decrease uric acid excretion and worsen hyperuricemia 5
• This can precipitate uric acid nephropathy and is never appropriate in TLS management 5
• Thiazides have no role in TLS treatment at any stage 5

Critical Monitoring Parameters

• Recheck potassium every 2-4 hours after initial treatment 5, 2, 3
• Comprehensive metabolic panel, phosphate, calcium, uric acid every 4-6 hours 2, 3
• Continuous ECG monitoring for hyperkalemia-induced arrhythmias 1, 5
• Monitor hourly urine output once dialysis restarts diuresis 2, 3

Critical Pitfalls to Avoid

• Never delay dialysis in anuric patients—waiting for medical management increases mortality risk from hyperkalemia-induced cardiac arrest 2
• Never alkalize urine in patients receiving rasburicase—this increases calcium-phosphate precipitation risk without benefit since rasburicase rapidly degrades uric acid 1, 2
• Never give calcium for hypocalcemia in the presence of hyperphosphatemia unless symptomatic—this causes metastatic calcification and worsens renal function 5, 2
• Never use loop diuretics to "restart" urine production in anuria—these patients need dialysis, not diuretics 1, 2