Question:
A 7-year-old on induction chemotherapy for ALL develops seizures. Labs: $\uparrow$phosphate, $\uparrow$uric acid, $\downarrow$calcium. What is the cause and best management?
A 7-year-old on induction chemotherapy for ALL develops seizures. Labs: $\uparrow$phosphate, $\uparrow$uric acid, $\downarrow$calcium. What is the cause and best management?
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Tumor Lysis Syndrome (TLS) Rules:
- Triad of elevation: $\uparrow\text{K}^+$, $\uparrow\text{PO}_4^{3-}$, $\uparrow\text{Uric Acid}$.
- One depression: $\downarrow\text{Ca}^{2+}$.
- Treatment rule for Calcium: Treat hypocalcemia ONLY if symptomatic, to prevent lethal calcium-phosphate precipitation in renal tubules!
- Triad of elevation: $\uparrow\text{K}^+$, $\uparrow\text{PO}_4^{3-}$, $\uparrow\text{Uric Acid}$.
- One depression: $\downarrow\text{Ca}^{2+}$.
- Treatment rule for Calcium: Treat hypocalcemia ONLY if symptomatic, to prevent lethal calcium-phosphate precipitation in renal tubules!
Updated On: Sep 3, 2026
- Hyperkalemia-induced seizure; give IV calcium gluconate
- Hypocalcemia due to tumor lysis; correct calcium only if symptomatic
- Hyperuricemia-induced CNS toxicity; start dialysis immediately
- Hypophosphatemia due to chemotherapy; give phosphate supplements
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The Correct Option is B
Solution and Explanation
Concept:
Tumor Lysis Syndrome (TLS) is an oncologic emergency resulting from the massive and rapid destruction of malignant cells following initiation of cytotoxic chemotherapy, particularly in hematologic malignancies like Acute Lymphoblastic Leukemia (ALL) and Burkitt lymphoma.
Explanation:
• Rapid intracellular release of ions and metabolic byproducts leads to the characteristic laboratory constellation: Hyperuricemia, Hyperkalemia, Hyperphosphatemia, and secondary Hypocalcemia.
• Secondary hypocalcemia develops because the massive surge of released intracellular phosphate complexes with circulating ionized calcium, causing calcium phosphate crystals to precipitate in soft tissues and renal tubules.
• Hypocalcemia increases neuromuscular excitability, manifesting clinically as tetany, laryngospasm, paresthesias, cardiac arrhythmias, and acute generalized seizures.
• In TLS management, hypocalcemia should strictly be corrected with intravenous calcium gluconate ONLY if the patient is overtly symptomatic (e.g., active seizures, tetany, or life-threatening arrhythmias).
• Asymptomatic hypocalcemia must NOT be treated with exogenous calcium because infusing calcium in the setting of severe hyperphosphatemia dramatically elevates the calcium-phosphate product ($[\text{Ca}] \times [\text{PO}_4] > 60$), precipitating extensive metastatic calcification in the kidneys and accelerating acute renal failure.
Final Answer:
The child's seizures are caused by acute hypocalcemia secondary to hyperphosphatemia in tumor lysis syndrome, and parenteral calcium correction should be reserved strictly for symptomatic patients.
Tumor Lysis Syndrome (TLS) is an oncologic emergency resulting from the massive and rapid destruction of malignant cells following initiation of cytotoxic chemotherapy, particularly in hematologic malignancies like Acute Lymphoblastic Leukemia (ALL) and Burkitt lymphoma.
Explanation:
• Rapid intracellular release of ions and metabolic byproducts leads to the characteristic laboratory constellation: Hyperuricemia, Hyperkalemia, Hyperphosphatemia, and secondary Hypocalcemia.
• Secondary hypocalcemia develops because the massive surge of released intracellular phosphate complexes with circulating ionized calcium, causing calcium phosphate crystals to precipitate in soft tissues and renal tubules.
• Hypocalcemia increases neuromuscular excitability, manifesting clinically as tetany, laryngospasm, paresthesias, cardiac arrhythmias, and acute generalized seizures.
• In TLS management, hypocalcemia should strictly be corrected with intravenous calcium gluconate ONLY if the patient is overtly symptomatic (e.g., active seizures, tetany, or life-threatening arrhythmias).
• Asymptomatic hypocalcemia must NOT be treated with exogenous calcium because infusing calcium in the setting of severe hyperphosphatemia dramatically elevates the calcium-phosphate product ($[\text{Ca}] \times [\text{PO}_4] > 60$), precipitating extensive metastatic calcification in the kidneys and accelerating acute renal failure.
Final Answer:
The child's seizures are caused by acute hypocalcemia secondary to hyperphosphatemia in tumor lysis syndrome, and parenteral calcium correction should be reserved strictly for symptomatic patients.
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