Treatment of congenital hypothyroidism

State and regional programs have been instituted in the United States and Canada for the screening of newborn infants for congenital hypothyroidism, and this topic was the subject of a recent report by the Committee on Genetics. The incidence of this disorder - averaged in several large series - is approximately 1 per 5,000 live births; therefore, these screening procedures represent a major advance in preventive medicine. Based on 3,160,000 live births in the United States in 1974, approximately 600 new cases of congenital hypothyroidism will be diagnosed each year through the screening programs and by recognition of affected infants by individual practitioners. These screening procedures result in earlier recognition of the disorder and thus a younger age at diagnosis; there also is increased knowledge about thyroid hormone homeostasis in the fetus and newborn infant. Therefore, it is appropriate to review dosage recommendations for treatment of infants with congenital hypothyroidism. In general, these recommendations are applicable to infants and young children with hypothyroidism regardless of the cause. The Committee on Drugs recommends the following: Physicians caring for children should participate in state, regional, or provincial screening programs for hypothyroidism and should maintain a high level of clinical suspicion to assure the earliest possible diagnosis of congenital hypothyroidism. Levothyroxine in a usual starting dose of 0.025 to 0.05 mg/day should be used for treatment. Dose adjustments should be made on the basis of patient response, particularly growth and development, and by measurements of serum T₄ level, bone age, and/or other appropriate laboratory determinations. Consideration should be given to interactions with other drugs and disease states so appropriate dose adjustments will be made.