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

Context: 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 mildCH casescan 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 CHandto 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