Thyroid function testing in neonates born to women with hypothyroidism.

UNLABELLED

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. What is Known: • Congenital hypothyroidism(CH) is the commonest preventable cause of childhood intellectual impairment. • Family history of hypothyroidism has been implicated as a risk factor for CH. • CH has formed part of newborn screening since the 1970s. What is New: • There is no research recommending thyroid function testing at 10-14 days of life to detect CH in neonates born to mothers with hypothyroidism. • Thyroid function testing at 10-14 days of life does not improve diagnostic yield for CH in babies born to mothers with hypothyroidism. • Newborn blood spot remains the mainstay for accurate and timely diagnosis of CH.