RESUMO
It has been proven that the newborn screening programs for congenital hypothyroidism are very important for its early detection and the early treatment of congenital It has been proven that the newborn screening programs for congenital hypothyroidism are very important for its early detection and the early treatment of congenital hypothyroidism can ameliorate and possibly reverse its consequences. Treatment with L-thyroxine is started in case of suspicious hypothyroidism at the first visit. Serum concentration of total and free thyroxine become normal within 1week after start of therapy but TSH values become normal from 2 months to 6 months after L-thyroxine therapy. The possible explanations for prolonged TSH elevation in congenital hypothyroidism are poor compliance for therapy, an inadequate dose of L-thyroxine, elevated threshold for thyrotropin suppression and two novel mutations in the thyrotropin (TSH) receptor gene in a child with resistance to TSH. Authors have experienced two cases of prolonged TSH elevation with normal T3 and T4 levels till 18months and 27 months of age after optimal L-thyroxine therapy and literature were reviewed.