Sir.—Children with leukemic hyperleukocytosis (>100 × 109/L) may have manifestations of hyperviscosity with disseminated intravascular coagulation, intracranial hemorrhage, and pulmonary insufficiency as well as the tumor lysis syndrome.1 Initial treatment before chemotherapy includes vigorous intravenous fluid therapy, allopurinol, and intravenous sodium bicarbonate to decrease the risk of uric acid nephropathy. Some patients have received leukapheresis, exchange transfusion, or cranial irradiation to treat or prevent the manifestations of hyperviscosity.1-5 A current protocol recommends leukapheresis or exchange transfusion if the cytocrit (volume of packed red blood cells and volume of packed white blood cells) is greater than 0.30.6
Three patients had a marked drop (52% to 89%) in leukocyte count during 1 to 2 days while receiving intravenous hydration, sodium bicarbonate, and allopurinol therapy and before receiving any chemotherapy. Thus, the more aggressive measures may be avoided in some patients who have no symptoms of hyperviscosity
LASCARI AD. Improvement of Leukemic Hyperleukocytosis With Only Fluid and Allopurinol Therapy. Am J Dis Child. 1991;145(9):969–970. doi:10.1001/archpedi.1991.02160090019009
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