Childhood IQ measurements in infants with transient congenital hypothyroidism.

OBJECTIVE: In view of the fact that, during the first period of life, thyroid hormones are critical for brain development, we investigated whether even transient congenital hypothyroidism could affect the long-term intellectual development of affected infants. DESIGN: A case-control study of intellectual development, auxometric parameters and thyroid function performed in late infancy in children with documented transient congenital hypothyroidism or hyperthyrotrophinaemia at birth. PATIENTS: Nine children born in an endemic goitre area who had short-term transient congenital hypothyroidism or hyperthyrotrophinaemia after birth (TCH) were studied and compared to nine matched children born in the same area at the same time but having normal thyroid function at birth (N). MEASUREMENTS: Global, verbal and performance IQs were evaluated on the Wechsler scale. Height, bone age, total and free thyroid hormones, thyroid volume, thyroglobulin, basal and TRH stimulated TSH were also measured. RESULTS: Height and bone age were similar in the two groups. Thyroid function tests were also similar in the two groups except for basal and TRH stimulated serum TSH and serum Tg which were higher in the TCH than in the control group. Global, verbal and performance IQs were systematically lower in the TCH than in the N group. (78.3 +/- 11.1 vs 90.9 +/- 14.2, P < 0.05; 84.4 +/- 15.4 vs 96.2 +/- 14.8, P NS; 75.0 +/- 8.5 vs 89.2 +/- 12.5, P < 0.01 respectively). CONCLUSION: Infants born and living in an academic goitre area, who had biochemical signs of thyroid hypo-function at birth, had a lower intelligence quotient at the age of 7-8 years than matched controls living in the same environmental conditions but with normal thyroid function at birth. The present findings strongly suggest that abnormalities in thyroid function at birth, even when transient, can adversely affect long-term intellectual development.

Personality traits and mental prognosis in patients with congenital hypothyroidism not treated from early life.

Congenital hypothyroidism, if not treated in very early life, severely impairs the neuropsychological development of affected subjects. We have carried out a detailed analysis of cognitive functioning and personality traits in 18 congenital hypothyroid patients treated late and/or unproperly. Significant cognitive defects were observed, the most important being a defective learning ability and an impaired capacity to judge socially significant events and to project complex actions in a temporal perspective. A mental retardation (IQ less than 70) was observed in 8/18 (44.4%) of these patients, a moderate intellective deficit in 5/18 (27.8%) and an IQ greater than 85 in the remaining 5 patients (27.8%). These data indicate that the mental defect of congenital hypothyroid patients may be overestimated. The patients personality was characterized by dependence on the mother, worrying about their body, maladjustment and socialization problems. Since the intellective prognosis of these patients may significantly improve when the environmental conditions are optimized, social and psychological help must always be suggested.