ESPE Abstracts

Background: Monitoring of thyroid function in neonates born from mothers affected by autoinmune thyroid disease is not perfectly established. The influence of etiology of maternal disease, maternal thyroid peroxidase antibodies (TPOAb) and l-thyroxine therapy during pregnancy on neonatal thyroid function were also investigated.

Method: 194 term neonates were tested for thyroid function by measurement of free thyroxine (FT₄), TSH in the 2nd day and one month of life. 167 neonates were born from mothers affected by chronic lymphocytic thyroiditis and 27 from mothers with Grave’s disease. TPOAb and thyroglobulin antibodies (TGAb) were measured in all patients, Thyroid Stimulating Inmunoglobulin (TSI) were also measured in newborns from mothers with Grave’s disease; periodical control of thyroid function were performed if TPOAb/TGAb were positive until they were negative or they were descended. Etiology of maternal hypothyroidism, maternal TPOAb and TGAb during pregnancy and dose of maternal therapy with L-thyroxine during pregnancy were retrospectively collected.

Results: 20% neonates showed at least a mild increase of TSH value (more than 6 mcU/ml) at the different determinations. 1.5% were newborns from mothers with Grave’s disease. Only three cases (1.5%) showed an increase of TSH value more than 10 mcU/ml, all of them born from mothers with chronic lymphocytic thyroiditis. In all of them, a spontaneous completely normalisation of TSH value was observed within the next determinations and they did not required L-thyroxine replacement therapy.

Conclusions: Transient mild elevation of serum TSH above the normal reference value for age is frequently observed in the first months of life in infants born from mothers affected by autoinmune thyroid diseases, but no so many need L-thyroxine replacement therapy. Follow-up is still recommended in these newborns.