A 7-year-old boy starts induction chemotherapy for a highly proliferative lymphoblastic tumour. Twelve hours later he develops oliguria. Which electrolyte pattern is most consistent with tumour lysis syndrome?

• A Hypernatremia, hyperkalemia, hypercalcemia
• B Hyperkalemia, hyperphosphatemia, hypocalcemia ✓
• C Hypokalemia, hyperphosphatemia, hypercalcemia
• D Hyperkalemia, hypophosphatemia, hypermagnesemia

Explanation

Massive lysis of malignant cells releases intracellular potassium and phosphate and converts purines to uric acid. Hyperphosphatemia drives calcium deposition and suppresses calcitriol, producing hypocalcemia, while potassium release causes potentially fatal hyperkalemia and renal failure worsens everything. Hypercalcemia argues against tumour lysis and points instead toward paraneoplastic mechanisms such as PTHrP production seen in some lymphomas and myeloma.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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