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

Management of Tumor Lysis Syndrome with Anuria

This patient has tumor lysis syndrome with anuria and requires immediate rasburicase administration plus urgent hemodialysis—loop diuretics like Lasix are contraindicated and will not work in an anuric patient. 1, 2

Clinical Recognition

This patient presents with the classic triad of tumor lysis syndrome (TLS):

• Hyperkalemia and hypocalcemia (at least 2 metabolic abnormalities define laboratory TLS) 1, 2
• Inability to urinate (anuria) indicates progression to clinical TLS, which is a medical emergency 1, 2
• High-risk malignancy (lymphoma receiving B-CHOP chemotherapy) 1, 2

Why Each Option is Right or Wrong

Option C: Rasburicase - CORRECT

Rasburicase must be administered immediately to all patients with clinical TLS. 1, 2 This is the single most important pharmacologic intervention because:

• Rapidly degrades uric acid within hours, preventing further renal damage from uric acid crystallization in the collecting ducts 1, 2
• Mean serum uric acid decreases from 15.1 to 0.4 mg/dL in hyperuricemic patients 1
• Prevents progression of acute kidney injury and may help restart diuresis as uric acid levels fall 3
• Works even in anuric patients because it enzymatically breaks down existing uric acid rather than relying on renal excretion 1, 2

Option A: Lasix (Furosemide) - INCORRECT

Loop diuretics are explicitly contraindicated in anuric patients and will waste critical time. 3 Here's why:

• Loop diuretics require functioning nephrons to work—they act on the loop of Henle to increase potassium excretion 3
• The guidelines specifically state: "Loop diuretics may be required to maintain urine output, except for patients with concomitant obstructive uropathy or hypovolemia" 3
• In anuria, there is no urine flow to augment, making furosemide completely ineffective 1
• This delays appropriate treatment (rasburicase and dialysis) while the patient's condition deteriorates 1

Option B: Thiazide - INCORRECT

Thiazides are even less appropriate than loop diuretics in this setting:

• Thiazides are weaker potassium-wasting diuretics than loop diuretics and are used for chronic hyperkalemia management in patients with adequate renal function 4
• They have no role in acute TLS management and are not mentioned in any TLS guideline 3, 1, 2
• Like loop diuretics, they require functioning kidneys and will not work in an anuric patient 4

Complete Management Algorithm

Step 1: Immediate Interventions (Within Minutes)

Administer rasburicase immediately without waiting for uric acid levels—the clinical picture is sufficient 1, 2:

• Standard dosing per TLS guidelines 1, 2
• Verify G6PD status first—rasburicase is contraindicated in G6PD deficiency 1

Stabilize cardiac membrane if severe hyperkalemia (≥6 mmol/L or ECG changes present) 3, 2:

• Calcium gluconate 50-100 mg/kg IV over 2-5 minutes 3, 2
• This does NOT lower potassium—it only protects the heart temporarily for 30-60 minutes 3, 2

Shift potassium intracellularly 3, 2:

• Insulin 0.1 units/kg IV plus 25% dextrose 2 mL/kg (onset 15-30 minutes, duration 4-6 hours) 3, 2
• Sodium bicarbonate ONLY if metabolic acidosis present (pH <7.35, bicarbonate <22 mEq/L)—otherwise it wastes time 3, 4

Step 2: Definitive Treatment (Within 1-2 Hours)

Initiate urgent hemodialysis 3, 1, 2:

• Hemodialysis is the most effective method for removing potassium and uric acid in anuric patients 3, 1, 2
• Uric acid clearance is 70-100 mL/min with HD, reducing plasma uric acid by ~50% per 6-hour treatment 3
• Oliguria/anuria rapidly responds to hemodialysis, often restarting diuresis as uric acid falls to 10 mg/dL 3
• Early initiation is critical to remove purine by-products and correct hyperkalemia, hyperphosphatemia, and hypocalcemia 3

Step 3: Supportive Management

Manage hypocalcemia cautiously 3:

• Asymptomatic hypocalcemia does NOT require treatment 3
• If symptomatic (tetany, seizures): calcium gluconate 50-100 mg/kg as single dose, repeated cautiously if necessary 3

Aggressive IV hydration through central venous access 2:

• Target urine output 100 mL/hour (3 mL/kg/hour in children <10 kg) once diuresis resumes 3, 2
• Start at least 48 hours before chemotherapy when possible, though rasburicase allows earlier chemotherapy if needed 2

Critical Pitfalls to Avoid

Never attempt diuresis with furosemide or thiazides in an anuric patient—this wastes time and delays appropriate treatment (rasburicase and dialysis) 1

Do not delay rasburicase while waiting for uric acid levels—the clinical picture of TLS is sufficient 1

Remember that calcium, insulin, and beta-agonists only temporize hyperkalemia—they do NOT remove potassium from the body and dialysis is still required 1, 2

Never use sodium bicarbonate without metabolic acidosis—it is ineffective and wastes time 4, 1

Verify G6PD status before rasburicase—it is contraindicated in G6PD deficiency 1

Monitoring Protocol

Recheck electrolytes every 2-4 hours initially 1, 2:

• Potassium, calcium, phosphate, uric acid 1, 2

Continuous ECG monitoring throughout acute management 3, 1

Monitor urine output closely once diuresis resumes 1, 2