Knowns and unknowns about congenital hypothyroidism: 2022 update

Abstract

Several excellent guidelines and expert opinions on congenital hypothyroidism (CH) are currently available. Nonetheless, these guidelines do not address several issues related to CH in detail. In this review, the authors chose the following seven clinical issues that they felt were especially deserving of closer scrutiny in the hope that drawing attention to them through discussion would help pediatric endocrinologists and promote further interest in the treatment of CH. 1. How high should the levothyroxine (L-T4) dose be for initial treatment of severe and permanent CH? 2. What is the optimal method for monitoring treatment of severe CH? 3. At what level does maternal iodine intake during pregnancy affect fetal and neonatal thyroid function? 4. Does serum thyroglobulin differ between patients with a dual oxidase 2 (DUOX2) variants and those with excess iodine? 5. Who qualifies for a genetic diagnosis? 6. What is the best index for distinguishing transient and permanent CH? 7. Is there any cancer risk associated with CH? The authors discussed these topics and jointly edited the manuscript to improve the understanding of CH and related issues.

Keywords: congenital hypothyroidism; iodine; levothyroxine; molecular genetics; the dual oxidase 2 (DUOX2).

Fig. 1.

Dot chart of serum Tg in patients with hypothyroidism with biallelic DUOX2 variants or iodine excess. The left chart shows the DUOX2 variant, and the right chart shows iodine excess. The values were drawn from previous reports (39, 54,55,56,57).