Medical and Pediatric Oncology 32:156 (1999) Letter to the Editor: Alkalinization and Tumor Lysis Syndrome We have read with interest the report about alkalinization and tumor lysis by Ten Harkel et al. . We would like to add the experience of the Hospital de Pediatrı́a J.P. Garrahan (Buenos Aires, Argentina) to the case reported by the above-mentioned authors. In a retrospective analysis of 99 consecutive patients with Burkitt lymphoma and Burkitt acute lymphoblastic leukemia (B-ALL) admitted from 1988 to 1996 to our institution, 12 patients (12.1%) presented the tumor lysis syndrome . All had Stage III–IV tumors or B-ALL. All patients received intravenous hyperhydration and urine alkalinization along with allopurinol on admission and usually for a few days after therapy was started. Chemotherapy according to BFM-based protocols was started as soon as the laboratory values and the patients condition stabilized. Nine patients had hyperuricemia at diagnosis, but serum uric acid values tended to decrease in the following days, and they were usually in the normal range after 3 days . Only two patients developed mild hyperuricemia after the start of treatment, whereas one patient had hyperphosphatemia at diagnosis, and three patients developed this complication after therapy was initiated. Serum creatinine rose in all these three patients, concomitantly, and all required hemodyalisis. However, we should acknowledge that serum phosphate values were measured in only eight patients overall. Two children had asymptomatic hypocalcemia at diagnosis, two developed symptomatic hypocalcemia after the start of treatment, and two others died of metabolic imbalances and multisystem organ failure. © 1999 Wiley-Liss, Inc. Even though virtually all of our patients had hyperuricemia, which can cause uric acid nephropathy and renal insufficiency, we feel that excessive urinary alkalinization may have played a role in the high incidence of renal failure in our children with hyperphosphatemia. This became evident within a few days of admission and probably potentiated the effect of hypocalcemia. We postulate that excessive urinary alkalinization may have caused calcium phosphate precipitation, leading to renal failure and therefore suggest that serum phosphate levels should be monitored carefully, especially after treatment has started. Excessive urinary alkalinization may be detrimental to renal function when hyperphosphatemia is present. Guillermo L. Chantada, MD Federico Sackmann-Muriel, MD Hematology/Oncology Department Hospital J.P. Garrahan Buenos Aires, Argentina REFERENCES 1. Ten Harkel ADJ, Kist Van Holte JE, Van Weel M, Van der Vorst MMJ. Alkalinization and the tumor lysis syndrome. Med Pediatr Oncol 1998;31:27–28. 2. Chantada G, Peña Siado J, Sackmann-Muriel F. Sı́ndrome de lisis tumoral en pacientes pediátricos con linfoma de Burkitt. Medicina Infantil (Buenos Aires) 1997;IV:161–165.