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Chapter 13: Tumor Lysis Syndrome

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Which of the following electrolyte disturbances are seen in TLS?

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A. Hyperkalemia, hypercalcemia, hyperphosphatemia

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B. Hyperkalemia, hypocalcemia, hyperphosphatemia

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C. Hypokalemia, hypocalcemia, hyperphosphatemia

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D. Hyperkalemia, hypocalcemia, hypophosphatemia

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The answer is B. The electrolyte disturbances found in TLS are due to the massive release of intracellular contents. Intracellular potassium is as high at 120 mEq/L and phosphorus concentrations can be up to four times higher intracellularly in malignant cells than in nonmalignant cells, resulting in hyperkalemia and hyperphosphatemia during cell lysis. Hypocalcemia develops in TLS as a result of calcium-phosphorus complexes in the setting of hyperphosphatemia.

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A 70-year-old man presents to the emergency department (ED) with fatigue, ecchymoses, and gum bleeding for 2 days. Vital signs are stable, and physical examination is notable for gingival hyperplasia, gum bleeding, splenomegaly, and petechiae on the lower extremities. Complete blood cell count (CBC) revealed WBC 150 × 109/L, hemoglobin of 8 g/dL, and platelets of 12,000/μL. Other notable laboratory data include sodium 134 mmol/L, potassium 5.6 mmol/L, bicarbonate 16 mmol/L, creatinine 1.2 mg/dL, calcium 6.9 mg/dL, phosphorus 8.2 mg/dL, and uric acid 13.4 mg/dL. Peripheral smear reveals the majority of cells are blasts. The patient is diagnosed with acute lymphoblastic leukemia (ALL). ECG does not reveal any abnormalities. Which of the following therapies should be initiated prior to chemotherapy?

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A. Crystalloid IVF and Kayexalate

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B. Crystalloid IVF and rasburicase

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C. Crystalloid IVF, allopurinol, and Kayexalate

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D. Crystalloid IVF, allopurinol, rasburicase, and hemodialysis

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The answer is B. The patient has a high risk malignancy and upon presentation presents with laboratory tumor lysis syndrome (uric acid >8 mg/dL, phosphorus >6.5 mmol/L, calcium <7.0 mg/dL, though potassium is no >6.0 mg/dL). Due to patient’s diagnosis, once chemotherapy is initiated he is at highest risk for developing clinical tumor lysis (AKI, cardiac arrhythmia, and/or neurologic events) which is why preventative measures are critical in this patient. Volume expansion is essential to support intravascular volume, renal blood flow and maintain glomerular filtration in an effort to optimize excretion of potassium, uric acid, and phosphate. Rasburicase is warranted as patient uric acid is elevated >8 mg/dL and his hyperuricemia is expected to worsen with treatment of his ALL. Allopurinol is generally used for patients with low or intermediate risk TLS, this patient has high risk TLS. Patient potassium is slightly elevated without any ECG abnormalities, close monitoring is needed but treatment with kayexalate or hemodialysis is not yet warranted.

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A 70-year-old man presents to the ...

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