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Reference Ranges of Reticulocyte Haemoglobin Content in Preterm and Term Infants: A Retrospective Analysis
Laila Lorenz1, Andreas Peter, Jörg Arand
1Department of Neonatology, University Children's Hospital, Tübingen University Hospital, Tübingen, Germany.
Insights
Reticulocyte haemoglobin content (Ret-He) is a reliable indicator for detecting iron deficiency in newborns. This parameter is not significantly affected by gestational age or common perinatal factors within the first 24 hours of life.
Area of Science:
- Neonatal Medicine
- Pediatric Hematology
- Clinical Chemistry
Background:
- Iron deficiency (ID) remains a concern in preterm infants despite supplementation.
- Optimal biomarkers for early ID detection in neonates are not well-established.
Purpose of the Study:
- Establish reference ranges for reticulocyte haemoglobin content (Ret-He) in preterm and term infants.
- Identify factors that may influence Ret-He levels in newborns.
Main Methods:
- Retrospective analysis of complete blood count and Ret-He.
- Infant blood samples were collected within 24 hours of birth.
- Analysis included infants of varying gestational ages.
Main Results:
- Mean Ret-He varied slightly across gestational age groups, with a 2.5th percentile of 25 pg.
- Gestational age showed a weak correlation with Ret-He (r=0.18).
- Ret-He demonstrated minimal correlation with C-reactive protein, IL-6, and umbilical artery pH, suggesting robustness.
Conclusions:
- The lower limit for normal Ret-He in newborns within 24 hours is 25 pg.
- Ret-He is a robust indicator of iron status, unaffected by gestational age or perinatal factors in the first day of life.
Background:
Despite iron supplementation, some preterm infants develop iron deficiency (ID). The optimal iron status parameter for early detection of ID has yet to be determined.
Objective:
To establish reference ranges for reticulocyte haemoglobin content (Ret-He) in preterm and term infants and to identify confounding factors.
Methods:
Retrospective analyses of Ret-He and complete blood count in infants with a clinically indicated blood sample obtained within 24 h after birth.
Results:
Mean (SD) Ret-He was 30.7 (3.0) pg in very preterm infants with a gestational age (GA) of <30 weeks (n = 55), 31.2 (2.6) pg in moderately preterm infants (GA 30-36 weeks, n = 241) and 32.0 (3.2) pg in term infants (GA ≥37 weeks, n = 216). The 2.5th percentile of Ret-He across all GA groups was 25 pg, with a weak correlation between Ret-He and GA (r = 0.18). Moreover, only weak/no correlations were found between Ret-He and C-reactive protein (r = 0.18), interleukin 6 (IL-6) (r = 0.03) and umbilical artery pH (r = -0.07). There was a slight variation in Ret-He with mode of delivery [normal vaginal delivery: 32.3 (3.2) pg, secondary caesarean section (CS): 31.4 (3.0) pg, instrumental delivery: 31.3 (2.7) pg and elective CS: 31.2 (2.8) pg].
Conclusion:
GA at birth has a negligible impact on Ret-He, and the lower limit of the normal reference range in newborns within 24 h after birth can be set to 25 pg. Moreover, Ret-He seems to be a robust parameter which is not influenced by perinatal factors within the first 24 h after birth.
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