Adult and child automated immature granulocyte norms are inappropriate for evaluating early-onset sepsis in newborns.

AIM: Automated haematology analysers are increasingly being used. Normal ranges for automated immature granulocyte counts (IG%) are described in adults and children as <1%, but are not reported for newborns, who often have complete blood count with differential in evaluation for early-onset sepsis. Therefore, this study aimed to describe IG% during the first 48 hours of life (HOL) in newborns and determine the clinical factors affecting IG%. METHODS: We carried out retrospective chart reviews for newborns ≥35 weeks gestational age with one or more complete blood count with differential in the first 48 HOL. Clinical history and automated haematology results were reviewed. RESULTS: Forty-seven of 215 subjects had two or more complete blood counts within 48 h. In the first 48 HOL, IG% ranged from 0 to 8.4% (95th percentile 5.2%). At <12 h, 70% of samples had IG% >1%. IG% appears to decrease over time. Earlier hour of life and higher birth weight were independently associated with higher IG%. CONCLUSION: Immature granulocyte counts in newborns appeared to be higher than reported for other age groups. Use of adult and child norms for IG% would not be appropriate for newborns being evaluated for early-onset sepsis.