Revised reference ranges for circulating neutrophils in very-low-birth-weight neonates

Area of Science:

• Neonatal Hematology
• Pediatric Immunology
• Clinical Pathology

Background:

• Standard neutrophil reference ranges, like Manroe's, may not accurately reflect the hematological status of very-low-birth-weight (VLBW) neonates.
• Previous assessments indicated a high incidence of neutropenia in healthy VLBW infants using existing reference ranges.

Purpose of the Study:

• To determine accurate reference ranges for circulating peripheral neutrophils in VLBW neonates from birth to 28 days of age.
• To compare these new ranges with established Manroe reference ranges and identify discrepancies.

Main Methods:

• Prospective collection of serial peripheral white blood cell counts from 193 inborn VLBW neonates (birth weight ≤ 1500 g).
• Analysis of 1788 neutrophil counts, divided into periods before (≤ 60 hours) and after ( > 60 hours) 60 hours of age.
• Exclusion of neonates with perinatal/neonatal complications to define ranges for healthy infants and comparison with Manroe's ranges.

Main Results:

• Immature neutrophil (ATI) and immature:total neutrophil (I:T) ratios were within Manroe's ranges.
• However, 67% of absolute total neutrophil (ATN) counts before 60 hours were below Manroe's lower limit, with 95% considered neutropenic.
• Newly established ATN ranges for VLBW neonates show wider distribution, particularly a lower lower boundary, and differ significantly from Manroe's ranges throughout the neonatal period.

Conclusions:

• Healthy VLBW neonates possess distinct ATN reference ranges compared to larger, older neonates, highlighting developmental effects on neutrophil dynamics.
• The established ranges provide a more accurate assessment of neutrophil counts in VLBW infants, potentially reducing misdiagnosis of neutropenia.
• Further research is needed to validate the predictability of neonatal infection using these novel reference ranges.