The hypothyroid infant and child; therapy with sodium l-thyroxine.

This communication reviews problems of diagnosis and therapy of hypothyroidism in infancy and childhood and presents 12 representative cases treated with sodium l -thyroxine. Pessimism in regard to treatment and prognosis for children with congenital athyrosis is based upon the high incidence of persisting deficits of intellect and skeletal growth which follow seemingly adequate replacement therapy. Selected experimental observations made in this laboratory regarding the physiologic role of thyroid in the growth and metabolism of I 131 -thyroid-ablated infant rhesus monkeys contribute to an understanding of clinical and metabolic features exemplified by these patients. In the athyroid infant monkey, as in the patients to be presented, it has been observed that many metabolic and clinical signs of thyroid deficiency may be controlled with doses of sodium l -thyroxine significantly smaller than those required to promote optimal central nervous system and skeletal growth and maturation.* This seeming discrepancy in tissue response