Thyroid function testing in neonates born to women with hypothyroidism

Our aim was to assess the utility of serum thyroxine and thyroid stimulating hormone performed at 10-14 days of life in diagnosing congenital hypothyroidism (CH) in babies born to mothers with hypothyroidism. This was a retrospective study of all babies born in a tertiary referral centre for neonatology over a 12-month period. Infants who had thyroid function testing (TFT) checked at 10-14 days of life because of maternal hypothyroidism during the period of study were included. The results of the newborn bloodspot and day 10-14 TFT were recorded along with whether or not patients were subsequently treated. Of the 319 patients included in the study, only two patients were found to have CH and in both cases the newborn blood spot had been abnormal. Conclusion: No extra cases of CH were detected from the thyroid test at 10-14 days and this practice should be discontinued due to the robust nature of existing newborn screening programmes.