title: Reference Ranges of Reticulocyte Haemoglobin Content in Preterm and Term Infants: A Retrospective Analysis.
abstract: 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.
  
  
  
  To establish reference ranges for reticulocyte haemoglobin content (Ret-He) in preterm and term infants and to identify confounding factors.
  
  
  
  Retrospective analyses of Ret-He and complete blood count in infants with a clinically indicated blood sample obtained within 24 h after birth.
  
  
  
  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].
  
  
  
  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.
authors.affiliation: Department of Neonatology, University Children's Hospital, Tübingen University Hospital, Tübingen, Germany.
authors.forename: Laila
authors.initials: L
authors.lastname: Lorenz
authors.forename: Andreas
authors.initials: A
authors.lastname: Peter
authors.forename: Jörg
authors.initials: J
authors.lastname: Arand
authors.forename: Fabian
authors.initials: F
authors.lastname: Springer
authors.forename: Christian F
authors.initials: CF
authors.lastname: Poets
authors.forename: Axel R
authors.initials: AR
authors.lastname: Franz
mesh_terms: D018798:Anemia, Iron-Deficiency / Q000097:blood; D002097:C-Reactive Protein / Q000032:analysis; D005260:Female; D005293:Ferritins / Q000097:blood; D005858:Germany; D005865:Gestational Age; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000097:blood*; D008297:Male; D012016:Reference Values; D012156:Reticulocytes / Q000737:chemistry*; D012189:Retrospective Studies; D047929:Term Birth / Q000097:blood*; D062606:Tertiary Care Centers
chemical_list: D006454:Hemoglobins; D002097:C-Reactive Protein; D005293:Ferritins