title: Establishment of hormone reference intervals for infants born < 30 weeks' gestation.
abstract: OBJECTIVE
  Preterm infants, especially those born very preterm (<32 weeks' gestation), suffer a number of morbidities. Immaturity of the endocrine system and its potential impact on morbidity is the subject of numerous studies. Hormone concentrations are sometimes measured in very preterm infants, however there are little normative data available to be able to interpret the results. The aim of this study was to describe age appropriate hormone reference intervals for babies born less than 30 weeks' gestation.
  
  
  METHODS
  Samples were collected at 1, 4, 7, 14, 21, 28 and 42 days after birth from babies born 23-29 weeks' gestation. The serum was analyzed for seven hormones by automated chemiluminescent immunoassay (Siemens Immulite 2000). Results from the 107 infants who survived beyond 40 weeks' corrected gestational age were included in the data analysis.
  
  
  RESULTS
  Cortisol, dehydroepiandrosterone sulfate, growth hormone and progesterone levels were highest during the first seven days with levels up to 10,801nmol/L; 26.6μmol/L; 343mU/L; and >63.6nmol/L respectively. Free thyroxine levels were as low as <2.6pmol/L for the first 28 days with the nadir at 7days. Estradiol levels ranged from <73 to 1626pmol/L over the six weeks. Reference intervals for IGF-1 could not be established as the levels were below the analyzer's sensitivity. There were no differences in reference intervals between male and female infants.
  
  
  CONCLUSIONS
  We describe gestation appropriate reference intervals for six hormones measured in babies born <30 weeks' gestation. Utilization of these reference intervals permits the correct and timely interpretation of results to the clinician.
authors.affiliation: School of Medical Sciences, RMIT University, Victoria, Australia; Murdoch Children's Research Institute, Melbourne, Australia.
authors.forename: Ronda F
authors.initials: RF
authors.lastname: Greaves
authors.affiliation: Murdoch Children's Research Institute, Melbourne, Australia; Department of Paediatrics, University of Melbourne, Victoria, Australia; Department of Endocrinology & Diabetes, The Royal Children's Hospital, Victoria, Australia.
authors.forename: Margaret R
authors.initials: MR
authors.lastname: Zacharin
authors.affiliation: Murdoch Children's Research Institute, Melbourne, Australia; Department of Paediatrics, University of Melbourne, Victoria, Australia.
authors.forename: Susan M
authors.initials: SM
authors.lastname: Donath
authors.affiliation: Murdoch Children's Research Institute, Melbourne, Australia; Dept of Pediatrics, Neurology and Radiology, WA University, St Louis, USA.
authors.forename: Terrie E
authors.initials: TE
authors.lastname: Inder
authors.affiliation: Murdoch Children's Research Institute, Melbourne, Australia; Department of Paediatrics, University of Melbourne, Victoria, Australia; Department of Obstetrics and Gynaecology, The Royal Women's Hospital, Victoria, Australia.
authors.forename: Lex W
authors.initials: LW
authors.lastname: Doyle
authors.affiliation: Murdoch Children's Research Institute, Melbourne, Australia; Department of Paediatrics, University of Melbourne, Victoria, Australia; Department of Newborn Intensive Care, The Royal Children's Hospital, Victoria, Australia. Electronic address: rod.hunt@rch.org.au.
authors.forename: Rodney W
authors.initials: RW
authors.lastname: Hunt
mesh_terms: D019314:Dehydroepiandrosterone Sulfate / Q000097:blood; D004703:Endocrine System / Q000254:growth & development* / Q000473:pathology; D004958:Estradiol / Q000097:blood; D005260:Female; D005865:Gestational Age; D013006:Growth Hormone / Q000097:blood; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D011374:Progesterone / Q000097:blood; D012016:Reference Values; D013974:Thyroxine / Q000097:blood
chemical_list: D011374:Progesterone; D004958:Estradiol; D019314:Dehydroepiandrosterone Sulfate; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D013974:Thyroxine; D006854:Hydrocortisone
keywords: Cortisol; DHEAS; Growth hormone; Prematurity; Thyroxine