At an increased risk: tumor lysis syndrome.

Patients at highest risk for tumor lysis syndrome (TLS) often are diagnosed with bulky, rapidly proliferating hematologic tumors, such as acute leukemia and nonHodgkin lymphoma (Kaplow & Hardin, 2007). Patients with solid tumors, such as mediastinal masses which are highly sensitive to chemotherapy, also may develop TLS, although it is more common in patients undergoing treatment for leukemia and lymphoma. TLS occurs from the effect of chemotherapy or radiation on rapidly dividing cells. Patients with elevated lactic dehydrogenase (LDH), dehydration, and renal insufficiency are at greatest risk for developing TLS (Brant, 2002). Advances in cancer treatment, such as those in bone marrow transplantation, require the use of high-dose chemotherapy, which may demonstrate an increase in the incidence of TLS. TLS is a rapidly developing oncologic emergency characterized by electrolyte and metabolic disturbances that are fatal without timely identification and management. Patients present with hyperuricemia, hyperphosphatemia, hypocalcemia, and hyperkalemia. Electrolyte disturbances can cause acute renal and multisystem organ failure (see Figure 1).