Background: Thyroid function in preterm infants is often altered for various reasons. LBW or VLBW newborns frequently present a particular form of congenital hypothyroidism (CH) characterized by low FT4 and delayed TSH elevation. The incidence of this disease is 1:250 for VLBW babies and 1:1589 for LBW newborns. In this condition, neonatal screening based solely on TSH can miss the diagnosis, therefore some screening programs have proposed to repeat the screening test 2 weeks after the first screening in preterm and/or LBW neonates. Nevertheless, in the literature there is disagreement about whether or not the retesting is necessary.
Objective and hypotheses: To evaluate the incidence of CH with delayed TSH elevation in North-Eastern Italy, and the need for a second screening strategy in LBW neonates.
Method: Since 2010, we have used a second screening strategy for newborns with birth weight <2500 g. First screening TSH cut-off was 9 mU/l, second screening TSH cut-off was 5 mU/l. Retrospective analysis of newborn thyroid screening data was performed.
Results: Thirty-seven newborns presented an increased TSH level at the second screening. The data was confirmed at serum control for 26 neonates, who started a L-thyroxine treatment. The incidence of CH with delayed TSH elevation in North-Eastern Italy was 1:586 for LBW, 1:215 for VLBW and 1:107 for ELBW. Between them 50% was newborns with a birth weight higher than 1500 g.
Conclusion: The second screening strategy for CH in preterm neonates proved useful in detecting newborns who otherwise would not be identified at first screening procedure. Moreover, it is interesting to note that more than a half of those who required a treatment had a birth weight higher than 1500 g. Finally the incidence of CH with delayed TSH elevation, in North-Eastern Italy, was superior to previous studies.
20 - 22 Sep 2014
European Society for Paediatric Endocrinology