Treatment of metabolic abnormalities with rasburicase in a premature neonate

Abstract

Transient leukemoid reactions are well-documented in the neonatal intensive care unit, however, hyperleukocytosis greater than 100 x 10⁹/L remains a rare entity in premature neonates. We report the development of extreme hyperleukocytosis in an extremely low birth weight premature neonate born at 24-2/7 weeks of gestational age due to premature rupture of membranes in a mother who had received antenatal corticosteroids. The patient subsequently developed gross dyselectrolytemia similar to tumor lysis syndrome. Infectious workup remained unrevealing, flow cytometry of the peripheral blood showed no immunophenotypic evidence of acute leukemia, and a normal female XX karyotype was confirmed. A single dose of rasburicase was administered, with rapid and safe resolution of hyperuricemia, allowing for maintenance of kidney function. The patient was treated for presumed sepsis, although cultures remained negative. The white blood cell count gradually normalized over the first two weeks of life. The patient required treatment for a patent ductus arteriosus and was severely ventilator dependent for 33 days post-partum. To our knowledge, this is the first documented case wherein electrolyte abnormalities similar to those seen in tumor lysis syndrome had complicated the course of a leukemoid reaction in an extremely premature neonate necessitating the use of rasburicase