LAUSR

To evaluate the role of serial newborn screening of congenital hypothyroidism using thyroxine (T4) in the neonatal intensive care unit (NICU). Newborn screen results were reviewed from a single academic NICU during 2007–2016 (n = 6100). Thyroid function levels were reviewed in patients treated for hypothyroidism during that period. Duration of treatment was followed after discharge. Overall incidence of treated hypothyroidism was 1:103 with increasing incidence inversely related to birth weight. Among treated infants (n = 59), initial newborn screen demonstrated sensitivity and specificity of 74.1% and 84.9%, respectively; second screen demonstrated rates of 85.7% and 76.1%, respectively. Based on follow-up data, prevalence of permanent congenital hypothyroidism in our NICU population was 1:870 (n = 7); two patients would have been missed with a single screen. Abnormal T4 on newborn screening is common for preterm neonates. Higher rates of permanent congenital hypothyroidism highlight the need for screening beyond the newborn screen.