Assessment of adaptive behavior in children with congenital hypothyroidism detected by neonatal screening and treated early in life. Comparison of effect of low and high doses of L-thyroxine on outcome

ABSTRACT

This study aimed at the evaluation of adaptive behavior in children with congenital hypothyroidism [CH] detected by neonatal screening and treated early in life with either low or high doses of L-Thyroxine. Thirty one patients ranging in age from 4 to 36 months of age and confirmed to have congenital hypothyroidism by neonatal screening were started on either low dose [8 micro g/kg/day] or high dose [15 micro g/kg/day] L-Thyroxine substitution and were followed up for growth and development. Using the Vineland Adaptive Behavior Scales [VABS], communication, social skills, daily living skills and motor skill acquisition were assessed and both groups were compared with a control group consisting of 30 normal infants and children closely matched for age and sex. The results showed that, in the low dose group, mean results for communication, social, daily living skills and motor acquisition were significantly lower than those for controls. In the high dose group, mean results for communication skills were significantly lower than those for controls, whereas other skills acquisition [social, daily living skills and motor skills] were not significantly lower than those for controls. Patients with thyroid aplasia fared much worse on all VABS parameters. However, those receiving high dose L-Thyroxine were pulled up to normal range. Lengths and weights were comparable to those of controls in both groups. We advocate early and high dose L-Thyroxine [15 micro g/kg/day] for the treatment of congenital hypothyroidism for a better neurodevelopmental outcome. These high doses achieve rapid euthyroidism which is essential in the early critical neonatal period. Levels can be later titrated according to laboratory results, with the aim of keeping levels in upper normal range for T4. Neonatal screening should be carried out as soon as possible afterbirth [3-5 days of life] to achieve the best response