Risk of iodine deficiency in extremely low gestational age newborns on parenteral nutrition

Iodine is an essential component of thyroid hormones, which play a critical role in neurodevelopment. The iodine status of pregnant women and their newborns is not checked routinely. Extremely Low Gestational Age Newborns do not receive Iodine supplementation while on parenteral nutrition (PN). We measured urine iodine levels and thyroid function tests in 50 mother–infant dyads at birth, at 1 week, 1, 2, 3 months and near discharge. We correlated maternal and neonatal urine iodine levels with thyroid functions and measured iodine levels in milk and PN. In our study, 64% of mothers were iodine deficient at the time of delivery, their free T4 levels were 0.48 (0.41–0.54) ng/dL with normal thyroid-stimulating hormone (TSH). Iodine levels were thirty-fold higher in extremely low gestational age newborns (ELGAN) exposed to iodine comparing to full terms (p < 0.001), but this effect lasted <1 week. At 1 month of age, ELGAN on PN developed iodine deficiency (p = 0.017) and had high thyroglobulin levels of 187 (156–271) ng/mL. Iodine levels improved with enteral feeds by 2 months of age (p = 0.01). Iodine deficiency is prevalent among pregnant women and ELGAN; in particular, those on PN are at risk of hypothyroidism. Iodine supplementation during pregnancy and postnatally should be considered to avoid iodine deficiency.