title: Developmental trends in cord and postpartum serum thyroid hormones in preterm infants.
abstract: The purpose of this study was first to clarify postnatal trends in sera T(4), free T(4) (FT(4)), T(4)-binding globulin, TSH, T(3), rT(3), and T(4) sulfate levels in cord and at 7, 14, and 28 d in groups of preterm infants at 23-27 wk (n = 101), 28-30 wk (n = 196), and 31-34 (n = 253) wk gestation, and second to compare these trends to those of term infants and also with cord sera levels of equivalent gestational ages (n = 812; 23-42 wk gestation). In all preterm groups, TSH and rT(3) decrease to below, T(4)-binding globulin increases to within, and T(3) and T(4) sulfate increase to above cord levels of equivalent gestational age. Term infants are hyperthyroxinemic relative to cord and nonpregnant adult levels of T(4). Postnatal T(4) increases are attenuated in 31- to 34-wk infants, absent in 28- to 30-wk infants (although levels are equivalent to gestational age), and crucially reversed in 23- to 27-wk infants. This immature group is hypothyroxinemic relative to other groups and to cord levels of equivalent gestational age. Compared with term infants, postnatal FT(4) increases are lower in 31- to 34-wk infants, attenuated in 28- to 30-wk infants, and absent in 23- to 27-wk infants. The 23- to 27-wk group is distinctive; they are hypothyroxinemic on T(4) levels, yet FT(4) levels are within the cord levels of equivalent gestational age.
authors.affiliation: Community Health Sciences, University of Dundee, Ninewells Hospital and Medical School, Dundee DD1 9SY, Scotland, United Kingdom.
authors.forename: Fiona L R
authors.initials: FL
authors.lastname: Williams
authors.forename: Judith
authors.initials: J
authors.lastname: Simpson
authors.forename: Caroline
authors.initials: C
authors.lastname: Delahunty
authors.forename: Simon A
authors.initials: SA
authors.lastname: Ogston
authors.forename: Jacoba J
authors.initials: JJ
authors.lastname: Bongers-Schokking
authors.forename: Nuala
authors.initials: N
authors.lastname: Murphy
authors.forename: Hans
authors.initials: H
authors.lastname: van Toor
authors.forename: Sing-Yung
authors.initials: SY
authors.lastname: Wu
authors.forename: Theo J
authors.initials: TJ
authors.lastname: Visser
authors.forename: Robert
authors.initials: R
authors.lastname: Hume
mesh_terms: D005312:Fetal Blood / Q000737:chemistry*; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D049590:Postpartum Period / Q000097:blood*; D013963:Thyroid Hormones / Q000097:blood*; D013972:Thyrotropin / Q000097:blood; D013975:Thyroxine-Binding Proteins / Q000032:analysis
chemical_list: D013963:Thyroid Hormones; D013975:Thyroxine-Binding Proteins; D013972:Thyrotropin