The value of serial newborn screening for congenital hypothyroidism using thyroxine (T4) in the neonatal intensive care unit

Objective To evaluate the role of serial newborn screening of congenital hypothyroidism using thyroxine (T4) in the neonatal intensive care unit (NICU). Subjects 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. Results 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. Conclusion 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.