The natural course of newborns with transient congenital hypothyroidism

A high rate of transient CH has been identified over the past decades following the lowering of TSH screening thresholds. The long-term outcome of transient CH has been evaluated in a few studies with inconclusive results. In the current study, we assessed the long-term outcomes of transient CH for up to 23 years. We found that 29% of cases were attributed to prematurity and 30% to subclinical hypothyroidism. No morphological anomalies were identified. Only syndromic patients (three with Down syndrome and one with Coffin-Lowry syndrome) required levothyroxine supplemental therapy at the time of the study, indicating that long-term thyroid function monitoring may be unnecessary. The high prevalence of neurodevelopmental impairment suggests the need for close neurodevelopmental monitoring in this population.