title: Nomogram-based evaluation of thyroid function in appropriate-for-gestational-age neonates in intensive care unit.
abstract: OBJECTIVE
  The objective of this study was to help neonatologists to interpret the thyroid hormone results accurately, and also to provide reference ranges and/or nomograms of FT4 (free thyroxine) and thyrotropin against gestational age at postnatal 1 week and 1 month in order to assess thyroid function in AGA (appropriate for gestational age) neonates in intensive care unit.
  
  
  METHODS
  This is a retrospective study. We included a total number of 515 AGA neonates between 24 and 42 weeks of gestation. Routine results of serum FT4 and TSH that had been analyzed with an immunoassay were collected from existing laboratory data. Least square regression analyses were used to estimate both the mean and the s.d. curves as polynomial functions of gestational age.
  
  
  RESULTS
  Free T4 levels were correlated with gestational age both at postnatal 1 week (r=0.39, P<0.001) and 1 month (r=0.26, P<0.001). Serum TSH levels at postnatal 1 week and 1 month did not show any correlation with gestational age. Scatterplots of FT4 levels against gestational age at 1 week and 1 month, showing the predicted 2.5th, 50th and 97.5th percentiles and central 95% reference ranges for TSH were provided.
  
  
  CONCLUSIONS
  Gestational age-specific nomograms for FT4 and reference ranges for TSH at postnatal 1 week and 1 month in AGA neonates have been developed. This can help neonatologists to interpret the thyroid hormone results accurately. Further studies providing reference ranges/nomograms for thyroid function in small-for-gestational-age neonates are needed.
authors.affiliation: Zeynep Kamil Maternity and Children's Training and Research Hospital, Neonatal Intensive Care Unit, Istanbul, Turkey.
authors.forename: E Y
authors.initials: EY
authors.lastname: Imamoglu
authors.affiliation: Department of Pediatrics, School of Medicine, Koç University, Istanbul, Turkey.
authors.forename: T
authors.initials: T
authors.lastname: Gursoy
authors.affiliation: Hacettepe Medical Faculty, Preventive Oncology Department, Ankara, Turkey.
authors.forename: M
authors.initials: M
authors.lastname: Hayran
authors.affiliation: Zeynep Kamil Maternity and Children's Training and Research Hospital, Neonatal Intensive Care Unit, Istanbul, Turkey.
authors.forename: G
authors.initials: G
authors.lastname: Karatekin
authors.affiliation: Zeynep Kamil Maternity and Children's Training and Research Hospital, Neonatal Intensive Care Unit, Istanbul, Turkey.
authors.forename: F
authors.initials: F
authors.lastname: Ovali
mesh_terms: D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007363:Intensive Care Units, Neonatal; D008297:Male; D049451:Nomograms; D012016:Reference Values; D012044:Regression Analysis; D012189:Retrospective Studies; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000502:physiology*; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood*
chemical_list: D013972:Thyrotropin; D013974:Thyroxine