Neonatal screening for congenital hypothyroidism (CH) in preterm infants. Is a targeted strategy required?

Background: Premature infants are at higher risk of developing congenital hypothyroidism (CH) but the neonatal screening strategy for this population is still debatable. The purpose of this retrospective study is to describe the results of a screening program for CH in a preterm infant cohort. Materials and Methods: All preterm newborns who underwent neonatal screening in the Italian region of Piedmont in the period January 2019 – December 2021, were included in this retrospective cohort study. The first TSH measurement was performed at 72h, while the second at 15 days of life. Infants with TSH >20 mUI/l at first detection and >6 mUI/l at second were recalled for a full evaluation of thyroid function. Results: During the study period, 5930 preterm newborns were screened. Based on birth weight (BW), the mean TSH was 2.08±0.15 for BW