A 55-year-old woman was hospitalized 2 days ago for initiation of chemotherapy. The patient was recently found to have a leukocyte count of 117,000/mm³, and a bone marrow biopsy confirmed the diagnosis of acute myeloid leukemia. She has been receiving combination chemotherapy for the past 2 days and has had nausea and several episodes of vomiting. The patient has also been receiving normal saline infusion at 100 mL/hr, rasburicase, and as-needed ondansetron since admission. She has no other medical problems and does not use tobacco, alcohol, or illicit drugs.
Blood pressure is 140/90 mm Hg, pulse is 100/min, and respirations are 18/min. The patient has conjunctival pallor and scattered petechiae. Urine output is approximately 50 mL/hr.
Laboratory results are as follows:
Which of the following is the most appropriate course of action?

Question

A 55-year-old woman was hospitalized 2 days ago for initiation of chemotherapy. The patient was recently found to have a leukocyte count of 117,000/mm³, and a bone marrow biopsy confirmed the diagnosis of acute myeloid leukemia. She has been receiving combination chemotherapy for the past 2 days and has had nausea and several episodes of vomiting. The patient has also been receiving normal saline infusion at 100 mL/hr, rasburicase, and as-needed ondansetron since admission. She has no other medical problems and does not use tobacco, alcohol, or illicit drugs.
Blood pressure is 140/90 mm Hg, pulse is 100/min, and respirations are 18/min. The patient has conjunctival pallor and scattered petechiae. Urine output is approximately 50 mL/hr.
Laboratory results are as follows:

Which of the following is the most appropriate course of action?

Quizplus · Accepted Answer

11ec193a_96d1_4f3c_853d_df9e71735d8d_MD0002_00 Tumor lysis syndrome (TLS) occurs when a large tumor burden undergoes rapid destruction with release of its intracellular contents into the bloodstream. Resulting electrolyte and metabolic abnormalities can cause acute kidney injury (eg, calcium-phosphate precipitation in renal tubules), arrhythmias (eg, calcium-phosphate precipitation in the heart), seizures, and possible sudden cardiac death. TLS is defined by >2 of the following: Uric acid >8.0 mg/dL (or 25% ↑ in baseline value [BV])Potassium >6.0 mEq/L (or 25% ↑ in BV)Phosphorus >4.5 mg/dL (or 25% ↑ in BV)Calcium <7.0 mg/dL (or 25% ↓ in BV) Uric acid >8.0 mg/dL (or 25% ↑ in baseline value [BV]) Potassium >6.0 mEq/L (or 25% ↑ in BV) Phosphorus >4.5 mg/dL (or 25% ↑ in BV) Calcium <7.0 mg/dL (or 25% ↓ in BV) < Strategies for TLS prevention are dependent on risk stratification (Table). Low-risk patients need only hydration with close monitoring, whereas intermediate-risk patients may receive hydration and allopurinol. High-risk patients should receive intravenous hydration and 5-7 days of prophylactic rasburicase, a recombinant uric acid oxidase that immediately catalyzes uric acid conversion into water-soluble allantoin and rapidly lowers uric acid levels. Although this high-risk patient (with acute myeloblastic leukemia with leukocytosis >100,000/mm³) received appropriate prophylactic therapy, she has elevated phosphorus and potassium as well as worsening renal function, concerning for impending TLS development. She should receive aggressive intravenous hydration with a urine output goal of >80-100 mL/hr as this helps decrease formation of uric acid and calcium-phosphate crystals. ³ (Choice A) In TLS, hemodialysis is indicated in patients with anuria, volume overload, or severe electrolyte abnormalities (eg, persistent hyperkalemia, calcium-phosphate product >70 mg²/dL²) despite optimal therapy. ² ² (Choice B) Allopurinol inhibits xanthine oxidase to prevent formation of uric acid and requires 3-4 days to become fully effective; it does not lower the preexisting uric acid levels. Regardless, this patient's uric acid level has already decreased, indicating that rasburicase was effective and should be continued. (Choice D) Phosphate- and potassium-binding therapies are recommended in patients with TLS with phosphorus >6.5 mg/dL and potassium >6 mEq/L. (Choice E) Sodium bicarbonate was previously recommended to alkalinize the urine with the goal of increasing uric acid solubility. However, this is no longer favored as alkalization can promote calcium-phosphate precipitation, especially in patients with marked hyperphosphatemia. In addition, normal saline is as effective in preventing uric acid crystallization. Educational objective: Patients at high risk for tumor lysis syndrome from chemotherapy should be treated with aggressive hydration (to maintain a urine output of >80-100 mL/hr), rasburicase, and careful clinical and biochemical monitoring. __________ References: Recommendations for the evaluation of risk and prophylaxis of tumour lysis syndrome (TLS) in adults and children with malignant diseases: an expert TLS panel consensus. (http://www.ncbi.nlm.nih.gov/pubmed/20331465) Guidelines for the management of pediatric and adult tumor lysis syndrome: an evidence-based review. (http://www.ncbi.nlm.nih.gov/pubmed/18509186)

A 55-Year-Old Woman Was Hospitalized 2 Days Ago for Initiation