Rasburicase is appropriate to treat hyperuricemia in this patient with tumor lysis syndrome (TLS). TLS is characterized by the massive release of uric acid, potassium, and phosphate into the blood from rapid lysis of malignant cells. It typically occurs after initiation of cytotoxic therapy for hematologic malignancies with large tumor burden (such as high-grade lymphomas) or high cell counts (such as acute lymphoblastic leukemia),