title: Evolution of thyroid function in preterm infants detected by screening for congenital hypothyroidism.
abstract: OBJECTIVE
  To determine the evolution of congenital hypothyroidism in preterms and the clinical features of permanent forms.
  
  
  METHODS
  We retrospectively evaluated 24 preterm children detected by newborn screening for congenital hypothyroidism: first screening with blood-thyroid stimulating hormone cutoff ≥10 mU/L and second screening with blood-thyroid stimulating hormone cutoff ≥5 mU/L. After the age of 2 years, patients with eutopic thyroid had diagnostic reevaluations, including thyroid function testing and thyroid ultrasonography after L-thyroxine therapy withdrawal.
  
  
  RESULTS
  The first screening identified 21.7% of patients with thyroid stimulating hormone elevation, and the second screening identified 73.9% of patients. One patient (4.4%) was identified with a third screening test; 21 patients had an eutopic thyroid and 3 patients a thyroid dysgenesis. At reevaluation, 5 patients (23.8%) showed permanent hypothyroidism (serum-thyroid stimulating hormone [s-TSH] >10 mU/L) resulting in the need to reintroduce therapy, 5 patients (23.8%) showed persistent hyperthyrotropinemia (s-TSH 5-10 mU/L), and 11 infants (52.4%) transient hypothyroidism (s-TSH <5 mU/L). The main clinical features of patients affected by permanent hypothyroidism were 1 case of assisted reproduction, 2 twins, 2 small for gestational age, 1 maternal thyroiditis, and 2 patients with malformations/syndromes.
  
  
  CONCLUSIONS
  Premature birth is a significant risk for congenital hypothyroidism with eutopic thyroid. In preterm infants, the evolution of congenital hypothyroidism remains difficult to predict. Our data emphasizes the high incidence of transient hypothyroidism in preterm infants, and the importance of diagnostic reevaluation to determine the definitive diagnosis.
authors: Department of Pediatrics, Vita-Salute San Raffaele University, IRCCS San Raffaele Hospital, Milan, Italy.
authors: Maria Cristina
authors: MC
authors: Vigone
authors: Department of Pediatrics, Vita-Salute San Raffaele University, IRCCS San Raffaele Hospital, Milan, Italy.
authors: Silvana
authors: S
authors: Caiulo
authors: Department of Pediatrics, Vita-Salute San Raffaele University, IRCCS San Raffaele Hospital, Milan, Italy.
authors: Marianna
authors: M
authors: Di Frenna
authors: Neonatal Intensive Care Unit Department of Clinical Sciences and Community Health, University of Milan, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
authors: Stefano
authors: S
authors: Ghirardello
authors: Regional Newborn Screening Laboratory of Lombardia Region, Children's Hospital V, Buzzi, Milan, Italy.
authors: Carlo
authors: C
authors: Corbetta
authors: Neonatal Intensive Care Unit Department of Clinical Sciences and Community Health, University of Milan, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
authors: Fabio
authors: F
authors: Mosca
authors: Department of Pediatrics, Vita-Salute San Raffaele University, IRCCS San Raffaele Hospital, Milan, Italy. Electronic address: weber.giovanna@hsr.it.
authors: Giovanna
authors: G
authors: Weber
mesh_terms: D015331:Cohort Studies; D003409:Congenital Hypothyroidism / Q000175:diagnosis* / Q000188:drug therapy / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D005865:Gestational Age; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D015997:Neonatal Screening / Q000379:methods*; D012189:Retrospective Studies; D018570:Risk Assessment; D013960:Thyroid Function Tests; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000627:therapeutic use; D016896:Treatment Outcome
chemical_list: D013972:Thyrotropin; D013974:Thyroxine