BACKGROUND AND OBJECTIVES: Many newborn screening (NBS) programs now perform repeat or serial NBS to detect congenital hypothyroidism. There is wide variation in thyroid-stimulating hormone (TSH) cutoffs used by NBS programs. Data on TSH reference ranges in preterm infants at increasing postnatal age are limited. Our study objective was to determine TSH reference ranges for preterm infants born at <32 weeks’ gestation. METHODS: We analyzed serial TSH levels on NBS performed on infants born between 22 and 31 weeks’ gestation from 2012 to 2016 in Wisconsin. The study cohort was divided into 2 groups (22–27 and 28–31 weeks), and TSH percentiles were defined from birth to the term equivalent gestational age. RESULTS: The study cohort consisted of 1022 and 2115 infants born at 22 to 27 and 28 to 31 weeks’ gestation, respectively. The 95th percentile TSH level for the group born at 22 to 27 weeks’ gestation gradually decreased and reached a nadir at ∼10 to 11 weeks. In contrast, for the group born at 28 to 31 weeks’ gestation, the 95th percentile TSH level reached a nadir at ∼5 to 6 weeks. At 3 to 4 weeks after birth, the 95th percentile TSH level ranged from 11 to 11.8 μIU/mL for the group born at 22 to 27 weeks’ gestation and ranged from 8.2 to 9 μIU/mL for the group born at 28 to 31 weeks’ gestation. CONCLUSIONS: Using a statewide cohort of preterm infants, we constructed TSH reference charts from birth to the term equivalent gestation for preterm infants born at <32 weeks’ gestation. Use of a single cutoff for all preterm infants might lead to misdiagnosis. The differences in TSH levels according to gestational-age categories might explain the increased frequency in congenital hypothyroidism diagnoses among preterm infants. These data are useful for defining age-adjusted NBS TSH cutoffs for preterm infants.

Objective The evidence on the role of early pulmonary vascular disease (PVD) in the development of late pulmonary hypertension (PH) in the extremely preterm infants is limited. Objectives were to determine the incidence of early and late PH in extreme preterm infants and to evaluate the role of early PH as a risk factor for development of clinically detected late PH. Methods It was a retrospective analysis of early echocardiograms (day of life 5–14) in preterm infants, 22 to 27 weeks' gestation, admitted to the University of Iowa NICU between July 01, 2012 to June 30, 2015. Late echocardiograms performed for clinical suspicion of PH were also analyzed. Results A total of 154 infants were included in the study. Early PH was diagnosed in 31 (20%) infants. Twenty-four (16%) infants were evaluated for clinically suspected PH. Eight (5%) infants were diagnosed with late PH. Infants with early PH had echocardiograms performed earlier than infants without the evidence of early PH. Early PH was not associated with the development of late PH (p = 0.99). Conclusion Early PH is common among extremely preterm infants (20%). Five percent of infants had clinically detected late PH. Infants with early PH had echocardiograms performed earlier than infants without the evidence of early PH. Early PH was not associated with the development of clinically detected late PH.