Leukemoid Reaction in Extremely Low-Birth-Weight Infants

Abstract

The objective of this paper was to determine the incidence of leukemoid reaction and to evaluate its relationship with maternal and neonatal factors in extremely low-birth-weight (ELBW) infants. The design a case-controlled retrospective 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 born during the study period, and are included in this report. The infants who demonstrated leukemoid reaction formed the study group, while the remainder formed the control group. Leukemoid reaction was defined as a white blood cell (WBC) count > or = 50,000/mm3. The relationship between maternal and neonatal variables and WBC counts was studied. Nine of the 60 infants studied demonstrated counts >50,000/mm3, with an incidence of 15%. There was no significant association demonstrated between maternal or neonatal variables and leukemoid reaction. Patients with leukemoid reaction 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 phenomenon, we could not demonstrate any relationship between these factors and high WBC counts, including sepsis and the use of antenatal steroids, the two most 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 those who did not.

Leukocytosis in very low birth weight neonates: associated clinical factors and neonatal outcomes

“…Different etiologies are suggested as causes for elevated WBC count in preterm infants. 7,8 We identified an association between antenatal steroids exposure and EL. Steroids are known to cause neutrophilia by accelerating release of leukocytes from bone marrow and reducing their egress from the blood into the tissue.…”

“…[7][8][9]12,14,15,27 The strengths of our study include large number of cases from two large NICUs, selective population of VLBW infants, differentiation of population into EL and LL and near completeness of neonatal outcome data. The matched cohort design ensured comparability between groups for the most important baseline and clinical characteristics.…”

“…On the basis of these varied definitions, the incidence of leukocytosis in VLBW neonates is reported to vary between 1.3 and 17%. 3,[7][8][9] Varied etiologies (infection, inflammation, drugs, stress) at different time points (antenatal or postnatal) may contribute to altered WBC count in neonates. 5,6,10 Acute infection, which could lead to rapid clinical deterioration and serious complications, is one potentially treatable condition among these etiologies.…”

Hyperleukocytosis in a premature infant with intrauterine herpes simplex encephalitis

“…This mother received antenatal steroids that have been proposed as being associated with leukemoid reactions, however, this possible association has not been confirmed in subsequent case series and mechanistic studies. 6,8,12 Given the initial elevation of the maternal WBC count and the microscopic analysis of the placenta, bacterial chorioamnionitis is a possible cause of the infant's high WBC count; however, all bacterial cultures were negative and there were no toxic granulations or vacuolization noted on the infant's peripheral blood smear. Chromosomal analysis was performed to rule out the possibility of leukemoid reaction related to mosaic trisomy 21 (result: 46XX).…”

“…4,5 Neonatal leukemoid reactions are not uncommon in ill neonates with prevalence estimates up to 15%. 6 Historically leukemoid reactions have been defined as a leukocyte count >50 Â 10 9 l À1 with no evidence of malignancy. 7 A more recent definition is an absolute neutrophil count (ANC)>10 s.d.s above the mean for gestational age (that is, ANC>30 000 in the first 60 h of life or ANC>15 000 from 60 h to 28 days of life).…”