Congenital hypothyroidism in Wales (1982-1993): demographic features, clinical presentation and effects on early neurodevelopment

OBJECTIVE Neonatal screening for congenital hypothyroidism (CH) was introduced in Wales in 1982. The aim of the study was to evaluate the demographic features and characteristics of infants identified during the first 12 years of screening and their neurodevelopmental progress in the first 2 years of life. DESIGN Prospective collection of biochemical and clinical data (including results of Griffiths Mental Development Scales) obtained from questionnaires sent to paediatricians responsible for the ongoing clinical care of children with On. PATIENTS In Wales, between 1982 and 1993, 136 infants with primary congenital hypothyroidism (CH) were identified by the neonatal screening programme. RESULTS Of all new-borns, 99.8% were screened and the prevalence of On was 1 in 3279(1 in 2473 girls and 1 in 4770 boys). The prevalence of CH was increased in North Wales. On was associated with increased birth weight (48.5% of infants weighed greater than 3.5 kg) and an increased prevalence of non-thyroidal congenital abnormalities (8%) and congenital heart disease (3%), Isotope scanning demonstrated an increased prevalence of normal or enlarged thyroid glands and fewer ectopic glands compared to those reported in other studies. The mean developmental quotients (DQs) for individual subsets of intellectual and behavioural functioning in children with CH aged 1 and 2 years were all above 100 (range: 103.5-111.9). In subjects with absent thyroids, these DQs were correlated with the serum concentrations of free thyroxine before treatment. CONCLUSIONS The demographic features of infants with congenital hypothyroidism born in Wares are similar to those reported from other European studies although there are marked regional variations in prevalence within Wales for which there is no apparent explanation. The median age of starting therapy was 17 days and compares favourably with other screening programmes, The overall mental development of Welsh children aged 1 and 2 years with congenital hypothyroidism identified by neonatal screening is satisfactory.