This patient requires treatment with high-volume normal saline and rasburicase because he has spontaneous tumor lysis syndrome triggered by rapid cell turnover from his acute myelogenous leukemia. Malignancies associated with rapid cell turnover can release large quantities of electrolytes and procoagulants into the circulation, causing the potentially life-threatening complication of tumor lysis syndrome. Tumor lysis syndrome may occur spontaneously with some cancers, but most often occurs after the initiation of cytotoxic therapy for tumors with a high proliferative rate, large tumor burden, or high sensitivity to cytotoxic agents. Therefore, treatment aimed at preventing tumor lysis syndrome should be considered prior to starting chemotherapy in patients at high risk. In tumor lysis syndrome, rapid cell breakdown results in hyperkalemia, hyperphosphatemia, hyperuricemia, hypocalcemia, and disseminated intravascular coagulation (DIC). Hyperuricemia can lead to urate nephropathy and acute kidney injury. Prevention or treatment involves aggressive hydration with normal saline to maintain renal perfusion and minimize uric acid or calcium phosphate deposition in the renal tubules. Because this patient already has evidence of kidney failure, hydration must be undertaken carefully to prevent significant volume overload. Hypouricemic agents are also indicated. Allopurinol is a competitive inhibitor of xanthine oxidase, which decreases the formation of new uric acid. Rasburicase is a urate oxidase (uricase) that catalyzes the breakdown of existing uric acid. Allopurinol is typically used in patients for prophylaxis for tumor lysis syndrome and in those without existing significant (>8 mg/dL [0.47 mmol/L]) elevations of serum urate. The more expensive rasburicase is usually used in patients with significantly elevated serum urate levels or in those with baseline kidney failure or in those with evidence of kidney injury related to tumor lysis, in order to rapidly decrease the serum urate level.
Fresh frozen plasma may be indicated if the patient develops DIC after initiating chemotherapy with resultant depletion of procoagulant. However, fresh frozen plasma would not treat tumor lysis syndrome and is only indicated when DIC is present. Based on this patient's normal serum fibrinogen level, this patient does not have DIC.
The initiation of multiagent chemotherapy prior to aggressive hydration and treatment with rasburicase is contraindicated in this patient who has acute kidney failure, likely due to tumor lysis syndrome, to prevent life threatening electrolyte abnormalities (such as hyperkalemia) associated with chemotherapy.
Platelet transfusions are indicated only for patients whose platelet count is less than 10,000/μL (10 × 109/L) or who develop spontaneous bleeding.