title: Congenital hypothyroidism due to defects of thyroid development and mild increase of TSH at screening: data from the Italian National Registry of infants with congenital hypothyroidism.
abstract: BACKGROUND
  Over the years lower TSH cutoffs have been adopted in some screening programs for congenital hypothyroidism (CH) worldwide. This has resulted in a progressive increase in detecting additional mild forms of the disease, essentially with normally located and shaped thyroid. However, the question of whether such additional mild CH cases can benefit from detection by newborn screening and early thyroid hormone treatment is still open.
  
  
  OBJECTIVE
  The aim of this study was to estimate the frequency of cases with mild increase of TSH at screening in the Italian population of babies with permanent CH and to characterize these babies in terms of diagnosis classification and neonatal features.
  
  
  METHODS
  Data recorded in the Italian National Registry of infants with CH were analyzed.
  
  
  RESULTS
  Between 2000 and 2006, 17 of the 25 Italian screening centers adopted a TSH cutoff at screening of <15.0 μU/mL. It was found that 21.6% of babies with permanent CH had TSH at screening of 15.0 μU/mL or less, whereas this percentage was 54% in infants with transient hypothyroidism. Among the babies with permanent CH and mild increase of TSH at screening (≤15 μU/mL), 19.6% had thyroid dysgenesis with serum TSH levels at confirmation of the diagnosis ranging from 9.9 to 708 μU/mL. These babies would have been missed at screening if the cutoff had been higher.
  
  
  CONCLUSIONS
  Lowering TSH cutoff in our country has enabled us to detect additional cases of permanent CH, a number of which had defects of thyroid development and severe hypothyroidism at confirmation of the diagnosis.
authors: Metabolism and Endocrinology, Istituto Superiore di Sanità, Viale Regina Elena, Rome, Italy. antonella.olivieri@iss.it
authors: Antonella
authors: A
authors: Olivieri
authors: Carlo
authors: C
authors: Corbetta
authors: Giovanna
authors: G
authors: Weber
authors: Maria Cristina
authors: MC
authors: Vigone
authors: Cristina
authors: C
authors: Fazzini
authors: Emanuela
authors: E
authors: Medda
mesh_terms: D003409:Congenital Hypothyroidism / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology*; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D007235:Infant, Premature, Diseases / Q000097:blood / Q000145:classification / Q000175:diagnosis; D007558:Italy / Q000453:epidemiology; D015997:Neonatal Screening / Q000379:methods; D012042:Registries; D012720:Severity of Illness Index; D050033:Thyroid Dysgenesis / Q000097:blood / Q000150:complications* / Q000175:diagnosis / Q000453:epidemiology*; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000002:abnormalities / Q000000981:diagnostic imaging; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood; D014463:Ultrasonography; D015854:Up-Regulation
chemical_list: D013972:Thyrotropin; D013974:Thyroxine