Leukemoid reaction in extremely low-birth-weight infants

The objective of this paper was to determine the incidence of leukemoid rea ction and to evaluate its relationship with maternal and neonatal factors i n extremely low-birth-weight (ELBW) infants. The design a case-controlled r etrospective study of all live-born ELBW infants (<1000 g) over a period of 2 years, from July 1994 to June 1996. A total of 60 preterm infants were b orn during the study period, and are included in this report. The infants w ho demonstrated leukemoid reaction formed the study group, while the remain der formed the control group. Leukemoid reaction was defined as a white blo od cell (WBC) count greater than or equal to 50,000/mm(3). The relationship between maternal and neonatal variables and WBC counts was studied. Nine o f the 60 infants studied demonstrated counts >50,000/mm(3), with an inciden ce of 15%. There was no significant association demonstrated between matern al or neonatal variables and leukemoid reaction. Patients with leukemoid re action had a better overall survival. Leukemoid reaction in ELBW infants is a rare and recently documented phenomenon. In our study the incidence was 15%. Although many factors have been postulated as a cause of this phenomen on, we could not demonstrate any relationship between these factors and hig h WBC counts, including sepsis and the use of antenatal steroids, the two m ost likely variables. It was interesting to note that the infants who were able to mount a leukemoid response had a better chance of survival than tho se who did not.