Abstract

In a study designed to provide retrospective control data for a neonatal thyroid screening programme, the problems of 141 hypothyroid children were examined. The mean IQ (Weschler intelligence scale) was 79.5 for children with congenital hypothyroidism but was normal in 6 children diagnosed before age 6 weeks. Diagnostic delay was associated with a steady decline in mean IQ but there was an improvement in some late diagnosed cases. A strong association was found between IQ and parental social class. Twenty five percent of the children were mentally retarded and 29% were at special schools; 54% of children at normal schools and 43% at special schools showed deviant behaviour. Other problems included clumsiness (26.2%) and squints (26.2%), and these were more common in children with a lower IQ. Congenital hypothyroidism is associated with persistent morbidity in many aspects of cerebral function. The adverse effects of prenatal hypothyroidism are largely reversible if treated before age 6 weeks.