Oral iodine supplementation in very low birth weight infants: Thyroid function and Neurodevelopmental follow up at 24 months. A Randomized Clinical Trial

Abstract

The trace element iodine (I) is essential for the synthesis of thyroid hormones. Premature babies need >30 μg I / kg /day (ICCIDD recommendations). Neonates and especially preterm infants are a population at risk of suffering the consequences of iodine de􀂦ciency, because of the impact of neonatal hypothyroxinemia on brain development. The main aim of this project is to prevent the mental retardation and increased risk of cerebral palsy of premature infants, which is partially caused by neonatal hypothyroxinemia. We gave Oral iodine supplementation in very premature babies during the neonatal period. Population: we included 94 infants born <1500g. Intervention group: we administered 30 μg I / kg /day of iodine in oral drops to 47 infants from 􀂦rst day of life until hospital discharge. Control group: 47 infants without supplements. The study was approved by the Ethics Committee. Samples of different formulas, maternal milk was kept for the determination of the iodine content. Interventions: Blood, food and urine samples (collected at 1, 7, 15, 21, 30 days after birth and at discharge). Measurements: milk and urine for iodine determination (Benotti method). Blood samples: for thyroid hormones (T4, free T4, T3 and TSH) and tyroglobulin. Their neurological development was assessed at 2 years of age (Bayley Test). Iodine content of mothers´ breast milk: 15 (5.0) μg I /dL (range 1-60); Infants in the supplemented group reached the recommendations from the 􀂦rst days of life. Infants in the control group did not reach the recommended intake of iodine to 60 days of life. We found a positive relation between iodine intake and the concentrations of thyroid hormones until 60 days of life. Conclusions: Thyroid function is related to iodine intake in preterm infants. Breast milk appears to be the best source of iodine for the premature infant. Preterm babies on formula preparations and with exclusive parenteral nutrition are at high risk of iodine de􀂦ciency. Therefore, supplements should be added if iodine intake is found to be inadequate.