ESPE Abstracts

Background: Congenital hypothyroidism (CH) is the most frequent endocrine disease in infants with prevalence ratio in the range of 1:2000–1:4000 new-borns. The disorder can be permanent (CHP) or transient (CHT). CH can be classified into two main groups: Dysgenesis, which accounts classically for 80–85% of cases and dyshormonogenesis for remaining 15–20%. From the last decade, studies described a upward trend for CH prevalence and changes in groups’ proportions.

Objective: To determine the updating prevalence of CH, CHP, CHT, dysgenesis, and dyshormonogenesis in infants confirmed with CH after newborn screening in a large French region (Midi-Pyrénées 31 000 births/year).

Method: Dysgenesis and dyshormonogenesis were defined as proposed in ESPE consensus and based on neonatal thyroid ultrasonography, thyroglobulin level, and scintigraphy. CHP categorised dysgenesis or dyshormonogenesis as infants with L-T₄ replacement necessary after 3 years of life and CHT when L-T₄ replacement is stopped between 1 and 3 years of life, with normal thyroid lab tests, ultrasonography, and scintigraphy with perchlorate discharge test.

Results: Between November 2002 and October 2011, 100 new-borns were confirmed with HC after TSH screening (62% females), Incidence is 1:2828 new-borns. Repartition was 51 dysgenesis (61% ectopy, 35% athyreosis, and 4% hypoplasia) and 49 eutopic gland (20 CHP and 29 CHT). Incidence for CHP (after 3 years) was 1:3983 infants. Congenital malformations in the whole group were found in 11% of neonates but none in the dysgenesis group. In the CHP group with dyshormonogenesis, molecular genetic studies identified seven genes mutations (NIS, three thyroglobulin, two TPO, and GNAS). In the CHT group, interestingly 1/3 of new-borns were premature babies and 2/3 were admitted in neonatal unit. Investigations confirmed the use of iodized antiseptic in these situations (for caesarean, neonatal surgery, or umbilical venous catheter).

Conclusion: We found in our large French region a CH incidence as closed to 1:3000 new-borns, similar to French CH incidence. We confirmed the trend to an increased proportion of eutopic gland compared to dysgenesis. When regarding only CHP, this proportion also remains higher to the one classically described.