What is the most appropriate management for a patient with lymphoma undergoing B-CHOP (Bendamustine, Cyclophosphamide, Hydroxydaunorubicin, Oncovin, Prednisone) chemotherapy, presenting with hyperkalemia, hypocalcemia, and acute kidney injury, in addition to hydration?

Management of Tumor Lysis Syndrome with Anuria

This patient requires immediate hemodialysis in addition to rasburicase, aggressive hyperkalemia management with insulin/glucose and calcium gluconate for cardiac membrane stabilization, and continuous ECG monitoring—loop diuretics are contraindicated in the setting of anuria. 1, 2

Immediate Dialysis Indication

Urgent hemodialysis must be initiated immediately because the patient has anuria despite hydration. 1, 2, 3, 4 The American Society of Nephrology explicitly recommends initiating hemodialysis urgently when oliguria or anuria develops despite aggressive hydration, as this represents established renal shutdown where medical management alone cannot prevent fatal hyperkalemia-induced cardiac arrest. 2, 3, 4

• Hemodialysis is also indicated for severe, refractory hyperkalemia (≥6 mmol/L unresponsive to medical management), which this patient likely has given the clinical TLS presentation. 2, 3, 4
• Uric acid clearance with hemodialysis is approximately 70-100 mL/min, and plasma uric acid falls by about 50% with each 6-hour treatment. 1
• Dialysis effectively removes both uric acid and phosphate through diffusive therapy, addressing the core metabolic derangements. 1

Rasburicase Administration

Administer rasburicase 0.2 mg/kg IV over 30 minutes immediately, even though dialysis is being initiated. 1, 2, 3, 5

• Rasburicase should be given to all patients with clinical TLS (defined as at least 2 biochemical abnormalities plus clinical complications such as renal failure). 1, 2, 3
• The drug rapidly degrades uric acid to allantoin within 4 hours in 96% of patients, preventing further uric acid crystallization in renal tubules. 5, 6
• Continue rasburicase for 3-5 days as needed based on uric acid levels. 3

Severe Hyperkalemia Management

For the hyperkalemia, immediately administer calcium gluconate 50-100 mg/kg IV over 2-5 minutes to stabilize the myocardial membrane, followed by insulin 0.1 units/kg IV plus 25% dextrose 2 mL/kg IV. 1, 2, 3, 4

• Calcium gluconate works within minutes to prevent arrhythmias but does not lower potassium levels—it only stabilizes cardiac membranes. 2, 3, 4
• Insulin/glucose combination begins lowering potassium within 15-30 minutes with duration of 4-6 hours. 3, 4
• Sodium bicarbonate can be added to correct acidosis and further stabilize myocardial membranes. 1
• Sodium polystyrene sulfonate 1 g/kg orally or by enema can be given but works slowly (hours) and is adjunctive only. 1, 4

Hypocalcemia Management

Do NOT treat the hypocalcemia unless the patient develops tetany, seizures, or prolonged QT interval. 1, 2, 4

• Asymptomatic hypocalcemia should never be treated in TLS because calcium administration can precipitate calcium-phosphate crystals in tissues and worsen renal injury. 2, 4
• Only if symptomatic (tetany, seizures), give calcium gluconate 50-100 mg/kg IV cautiously and repeat if necessary. 1, 4

Critical Monitoring Parameters

Continuous ECG monitoring is mandatory to detect hyperkalemia-induced arrhythmias. 1, 2

• Recheck potassium every 2-4 hours after initial treatment. 2, 3, 4
• Obtain comprehensive metabolic panel, phosphate, calcium, uric acid, and LDH every 4-6 hours for the first 24 hours. 2, 3, 4
• Monitor hourly urine output (though currently zero) to assess for recovery of renal function. 2

Critical Pitfalls to Avoid

Never use loop diuretics in this anuric patient—the guidelines explicitly state loop diuretics should NOT be used in patients with anuria or oliguria despite adequate hydration. 2, 3, 4 Loop diuretics are only appropriate when the patient is adequately hydrated, has no obstructive uropathy, and maintains some urine output. 1

Never alkalize the urine with sodium bicarbonate for uric acid management when using rasburicase—this increases calcium phosphate precipitation risk without providing benefit since rasburicase rapidly degrades uric acid to allantoin. 2

Never delay dialysis waiting for medical management to work when the kidneys have shut down—this increases mortality risk from hyperkalemia-induced cardiac arrest. 2

Hyperphosphatemia Management

• Mild hyperphosphatemia (<1.62 mmol/L) does not require treatment. 1
• More severe hyperphosphatemia can be treated with aluminum hydroxide 50-100 mg/kg/day divided in 4 doses orally or by nasogastric tube. 1
• However, in the setting of anuria, dialysis is the only effective method for rapidly lowering phosphate levels. 7