Title: Intellectual development in children with congenital hypothyroidism in relation to recommended thyroxine treatment
Abstract: The relationship between the treatment serum thyroxine level and intellectual development at 2 and 6 years was investigated in 46 Norwegian children with congenital hypothyroidism identified by neonatal screening. The level of serum thyroxine during the first 2 years was positively correlated with the Mental Development Index at 2 years of age (Bayley Scales of Infant Development) and the Verbal IQ at 6 years of age (Wechsler Preschool and Primary Scale of Intelligence). Children with a mean serum thyroxine level greater than 180 nmol/L (14 micrograms/dl) during the first year had a significantly higher Mental Development Index at 2 years and Verbal IQ at 6 years than children with serum thyroxine values less than 129 nmol/L (10 micrograms/dl). Boys had a lower Mental Development Index at 2 years of age than girls (86.9 vs 105.1; p less than 0.001) and a higher frequency of elevated serum levels of thyroid-stimulating hormone during the first year (p = 0.001). No signs of toxic effects of a high hormone level at the time of IQ assessment were detected. However, high serum levels of thyroxine at ages 2 to 4 years in girls were related to lower Performance IQ at age 6 years. The results demonstrate that the serum level of thyroxine is of importance in relation to intellectual development. Thyroxine levels above the upper reference range during the first 2 years were related to best intellectual development at 2 and 6 years.
Publication Year: 1991
Publication Date: 1991-06-01
Language: en
Type: article
Indexed In: ['crossref', 'pubmed']
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Cited By Count: 125
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