Sunday, December 6, 2015

Q: Tumor lysis syndrome (TLS) is an oncologic emergency. All of the following electrolyte derangements can occur in TLS except?

A) Hyperphosphatemia
B) Hypercalcemia
C) Hyperkalemia
D) Hyperuricemia
E) Xanthinuria

Answer: B

Hyperphosphatemia and consequently hypocalcemia are one of the hallmark of TLS. The phosphorus concentration in malignant cells are much higher than in normal cells. Its combination with calcium (calcium-phosphate) causes marked hypocalcemia. Actually it is calcium-phosphate precipitation in the renal tubules which leads to AKI (acute kidney injury) in TLS. If calcium phosphate product goes to more than or equal to 70 mg2/dL2, CRRT should be strongly considered. 

 With breakdown of cells, life threatening hyperkalemia and hyperuricemia may occur. Most patients with TLS receives allopurinol which causes xanthine precipitation in the tubules.

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