Trials with thyroid hormone in preterm infants: clinical and neurodevelopmental effects.

A large number of articles exist on thyroid hormone function and its clinical correlates, but only a few exist on trials with thyroid hormones in premature infants. Most of these trials had clinical short-term endpoints, while only one trial had a long-term neurodevelopmental endpoint. None of the trials reported changes in mortality and morbidities. A trend toward a lower occurrence of patent ductus arteriosus is found in thyroid hormone treated infants. A gestational age-dependent effect of thyroxine on neurodevelopmental outcome was found in post-hoc subgroup analyses up until the age of 10 years. Thyroxine treatment was associated with improved mental, motor, and neurological outcomes in infants <28 weeks gestation, but with worse mental and neurological outcome in infants of 29 weeks gestation. Future trials should focus on neurodevelopmental outcomes. Continuous administration of thyroid hormone may be more effective than bolus administration.