Neuropsychological assessment in congenital hypothyroid children: importance of timing of replacement therapy

Introduction: Early diagnosis by neonatal thyroid screening is crucial for intellectual and neuropsychological outcome of children with congenital hypothyroidism (CH). Nevertheless, numerous reports have shown that some CH children, even if early treated, still have neuropsychological sequelae at a later age. In this study, we investigate whether the occurrence of a delayed onset of therapy, despite newborn screening, can be responsible for psychomotor abnormalities. Subject and methods: Intellectual and neuropsychological development was assessed in a group of 29 CH children diagnosed by screening in a defined Italian region, in 3 CH children detected on the basis of clinical symptoms and in 11 CH adults born before the screening program was introduced. Thyroid assessment and clinical examination were also performed in these patients. Results: The screened CH children with delayed therapy onset (range:40–70 days) had mostly ectopic and eutopic thyroids and showed significantly lower mean intelligence quotients (90.8 ± 16 vs 106.2 ± 13) and lower mean scores on neuropsychological tests than earlier treated CH children (range: 7–30 days). Discussion: Our study points out that children with ectopic thyroid and dyshormonogenesis, although showing a milder thyroid deficit at screening, may be at risk for delayed onset of therapy and consequent cognitive damage prompt, and adequate treatment should be given in all types of primary CH to prevent mental disturbances in CH children.