Objective. To compare the effects of therapy with thyroxine (T4) plus triiodothyronine (T3) versus T4 alone from the first days of life in screened congenital hypothyroid (CH) infants.

Methods. We examined 14 CH infants diagnosed by neonatal screening and a group of control infants. CH patients were divided randomly into 2 groups, 1 treated with T4 alone (group 1) and the other treated with T4 plus T3 (liothyronine; group 2). In all patients electrocardiography and thyroid hormone evaluations were performed before and 15 and 30 days and 3, 6, and 12 months after the beginning of therapy. Psychological tests were also performed at 6 and 12 months of age in CH patients and in other matched controls.

Results. After 15 days of treatment, serum thyrotropin (TSH) levels become normal in 5 of 7 cases of group 1 (median TSH level 10.7 μU/ml) and in 1 of 7 cases of group 2 (median TSH level 72.5 μU/ml). At the same period, serum-free thyroid hormone levels were within the normal range in both groups, but free T4 values were significantly higher in group 1 than in group 2 and in controls. At the subsequent examinations, free T4 values were within the upper normal limit in group 1, whereas they remained within the normal range in group 2. No clinical or electrocardiographic signs of heart disease were found in any of the patients. The psychometric quotient in CH infants was significantly lower than in controls, but similar in patients of group 1 and group 2.

Conclusions. The combined treatment with T4 plus T3 seems not to show significant advantages, at least in our experimental conditions, compared with the traditional treatment with T4 alone in early treated CH infants. A further longer and more extensive follow-up is mandatory.

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