Thyroid Function in Healthy and Sick Very-Low-Birth-Weight Infants – Thyrotropin and Free Thyroxine Levels until the Sixth Week of Age

Abstract

Hypothyroxinemia in preterm infants without congenital hypothyroidism is associated with developmental delay. Longitudinal information on thyroid function in very-low-birth-weight (VLBW, <1,500 g birth weight) infants is limited: we present data on thyroid function in sick and healthy VLBW infants until 6 weeks of age. Free T(4) and TSH levels routinely obtained on days 14-21 and days 35-49 in 92 consecutive VLBW infants were correlated retrospectively with neonatal morbidity. Free T(4) levels were positively correlated with gestational age; an independent effect of neonatal disease on thyroid function was not detectable.