Neurodevelopmental assessment of patients with congenital hypothyroidism

Congenital hypothyroidism (CH) is the most common cause of preventable cognitive disability worldwide. Generally, it is produced by an alteration in the embryogenesis of the thyroid gland or by an alteration in the synthesis of thyroid hormones, which determine that affected patients have low or absent thyroid hormone concentrations. The importance of this fact is that brain development during the first three years of life is highly dependent on thyroid hormones. Prior to the implementation of national neonatal screening programs around the world, 8 to 27% of children with CH had an IQ lower than 70. Nowadays, this percentage is close to 0 in countries that have implemented the program. In Chile, CH neonatal screening program achieved national coverage in 1996. Currently, the incidence of the disease in our country is 1: 3163. The degree of disability produced by CH not only depends on the time of detection of the disease and the prompt start of therapy, but also on an adequate monitoring. Despite screening programs, neurocognitive impairment in schoolchildren and teenagers with CH is still observed, reflected in lower scores in cognitive, language and gross motor assessments, receptive communication, expressive communication, fine motor and gross motor skills compared to healthy children. Also, lesser achievements in learning and language disorders are observed. The objective of this review is to update the information available on neurodevelopment of patients with CH.