title: Neurodevelopmental and body composition outcomes in children with congenital hypothyroidism treated with high-dose initial replacement and close monitoring.
abstract: BACKGROUND
  Despite newborn screening and early levothyroxine replacement, there are continued reports of mild neurocognitive impairment in children with congenital hypothyroidism (CHT). In Auckland, New Zealand, cases are identified by a neonatal screening program with rapid institution of high-dose levothyroxine replacement (10-15 μg/kg·d), producing prompt normalization of thyroid function. Subsequently, frequent monitoring and dose alterations are performed for 2 years. We aimed to assess whether the Auckland treatment strategy prevents impairment of intellectual and motor development.
  
  
  METHODS
  This study encompassed all children with CHT born in 1993-2006 in Auckland and their siblings. Neurocognitive assessments included the following: 1) intelligence quotient via Weschler Preschool and Primary Scale of Intelligence III or Weschler Intelligence Scale for Children IV; 2) Movement Assessment Battery for Children; and 3) Beery Developmental Test of Visual-Motor Integration. Body composition was assessed by dual-energy x-ray absorptiometry.
  
  
  RESULTS
  Forty-four CHT cases and 53 sibling controls aged 9.6 ± 3.9 years were studied. Overall intelligence quotient was similar among CHT cases and controls (95.2 vs 98.6; P = .20), and there were also no differences in motor function. Severity of CHT did not influence outcome, but greater time to normalize free T4 was associated with worse motor balance. There were no differences in anthropometry or body composition between groups.
  
  
  CONCLUSIONS
  These findings suggest that a strategy of rapidly identifying and treating infants with CHT using high-dose levothyroxine replacement is associated with normal intellectual and motor development. The subtle negative impact on motor function associated with time to normalize free T4 levels is consistent with benefit from rapid initial correction.
authors.affiliation: Liggins Institute, Faculty of Medical and Health Sciences, University of Auckland, 1023 Auckland, New Zealand.
authors.forename: Benjamin B
authors.initials: BB
authors.lastname: Albert
authors.forename: Natasha
authors.initials: N
authors.lastname: Heather
authors.forename: José G B
authors.initials: JG
authors.lastname: Derraik
authors.forename: Wayne S
authors.initials: WS
authors.lastname: Cutfield
authors.forename: Trecia
authors.initials: T
authors.lastname: Wouldes
authors.forename: Sheryl
authors.initials: S
authors.lastname: Tregurtha
authors.forename: Sarah
authors.initials: S
authors.lastname: Mathai
authors.forename: Dianne
authors.initials: D
authors.lastname: Webster
authors.forename: Craig
authors.initials: C
authors.lastname: Jefferies
authors.forename: Alistair J
authors.initials: AJ
authors.lastname: Gunn
authors.forename: Paul L
authors.initials: PL
authors.lastname: Hofman
mesh_terms: D001823:Body Composition / Q000187:drug effects* / Q000502:physiology; D002648:Child; D002675:Child, Preschool; D003409:Congenital Hypothyroidism / Q000188:drug therapy* / Q000503:physiopathology; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007360:Intelligence / Q000187:drug effects* / Q000502:physiology; D007361:Intelligence Tests; D008137:Longitudinal Studies; D008297:Male; D015997:Neonatal Screening; D009483:Neuropsychological Tests; D009520:New Zealand; D011597:Psychomotor Performance / Q000187:drug effects* / Q000502:physiology; D012720:Severity of Illness Index; D013960:Thyroid Function Tests; D013974:Thyroxine / Q000008:administration & dosage / Q000627:therapeutic use*
chemical_list: D013974:Thyroxine