Congenital hypothyroidism: treatment and outcome

Purpose of review The purpose of this review is to summarize findings from research on children with congenital hypothyroidism diagnosed by newborn screening, to relate specific findings to aspects of treatment and follow-up, and to identify areas for concern and directions for future research. Recent findings Although early studies following children with congenital hypothyroidism identified by screening indicate improved outcome relative to cases diagnosed clinically, these children still have a mild IQ loss, which can be attenuated somewhat by an early high-dose level of thyroxine therapy. Additionally described are a number of subtle, selective, and persisting cognitive deficits that vary in type among the studies. Nevertheless, there is a consensus that disease severity and timing of onset predict different deficits than age at starting therapy and initial dose level. Although a series of newer second-generation papers report favorable outcomes when treatment factors are well controlled, sampling issues, age and thyroid status at testing, and aspects of testing all influence the results. Important outstanding issues include the optimal therapy for less severely affected cases and ensuring a high quality of subsequent care. Five areas for future research are highlighted. Summary Although early treatment of congenital hypothyroidism leads to improved outcome, minor deficits may arise from insufficient thyroid hormone before birth and during infancy. It is important to conduct large-scale multicenter investigations to identify and measure the critical factors affecting outcomes in this population.