THYROXINE SUPPLEMENTATION IN INFANTS <30 WEEKS GESTATIONAL AGE: NEURODEVELOPMENTAL OUTCOME AT 2 YEARS OF AGE. • 1679

Abstract

Background: Transient hypothyroxinemia is a common phenomenon in preterm infants. An association has been found between low neonatal T4 levels and an increased risk of impaired developmental outcome. Until now however, it is unclear whether T4 administration is required in preterm infants.Methods: We carried out a randomized, placebo-controlled, double-blind trial. 200 infants <30 weeks gestational age were enrolled. Administration of T4/placebo was started 12-24 hours after birth at a daily dose of 8 μg per kg birthweight per day and discontinued 6 weeks later. Neurological examinations were carried out at term, and at the corrected ages of 6, 12, and 24 months of age. Bayley developmental scales were performed at the latter 3 time points. Results: After the NICU-period 85 infants remained in the T4 group and 76 in the Placebo group. The 2 study groups did not differ with respect to birthweight, gestational age, sex, social and racial background, neonatal disease and cerebral hemorrhage and ischaemia. Mental nor psychomotor development differed between the 2 groups. At term age and at 24 months a significant reduction of abnormal neurological outcome was found in the T4 group (p=0.019 and 0.014 resp.). Also, a reduction of adverse outcome (death or an abnormal mental and neuromotor outcome) was found in the T4 group (RR 0.62, 95%-CI: 0.35-0.99). Conclusions: T4 administration to very preterm infants does not alter developmental outcome, but is associated with an improvement of neurological and adverse outcome at 24 months of age.