Avoiding the Overdiagnosis of Congenital Hypothyroidism in Premature Newborns.

Abstract

Listen

Translate article

* Abbreviations: CH — : congenital hypothyroidism NBS — : newborn screening TSH — : thyrotropin VLBW — : very low birth weight Nowadays, most programs use thyroid-stimulating hormone (TSH) as the primary analyte in newborn screening (NBS) for congenital hypothyroidism (CH); however, unlike for 17-hydroxy-progesterone levels used in NBS to diagnose 21-hydroxylase deficiency,1 gestational age-specific cutoffs have not been defined. In this issue of Pediatrics , Kaluarachchi et al2 publish TSH reference ranges at NBS for preterm infants until they reach term equivalent gestational age. This study is based on multiple dried blood-spot TSH samples, as suggested by international guidelines,3 to detect the delayed TSH rise that has been described in preterm infants. The main finding of this study is that the 99th centile of estimated serum TSH (assuming a 55% hematocrit) is ∼30.6 mU/L on the first sample collected at 24 to 96 hours in infants born at 28 to 31 weeks and 41.6 mU/L in those born at 22 to 27 weeks. To avoid any confusion, the latter figure corresponds to 18.9 mU/L when translated back to milliunits per liter of whole blood (the way … Address correspondence to Guy Van Vliet, MD, Center Hospitalier Universitaire Sainte-Justine, Room 3740, 3175 Chemin de la Cote-Ste-Catherine, Montreal, QC H3T 1C5, Canada. E-mail: guy.van.vliet{at}umontreal.ca