Massive hyperphosphatemia in clinical tumor lysis syndrome during prophylactic rasburicase use: risk factors and treatment options

We report the case of a 76-year-old female with diffuse large B cell lymphoma who developed tumor lysis syndrome (TLS) and subsequent acute kidney injury (AKI) due to massive hyperphosphatemia during the prophylactic use of rasburicase. Our case showed no hyperphosphatemia before chemotherapy but had elevated uric acid and creatinine levels and unilateral hydronephrosis due to paraaortic lymphadenopathy. TLS risk was classified as high risk because of bulky mass, LDH elevation, and renal disturbance. With rasburicase use, uric acid was completely controlled but massive hyperphosphatemia and, subsequently, AKI developed. Immediate kidney replacement therapy led to improvement of hyperphosphatemia and AKI. In the rasburicase era, hyperphosphatemia has been a key target for preventing and treating TLS. Renal replacement therapy is the only effective option for lowering hyperphosphatemia and treating AKI.