Benefits and Risks of Thyroid Scintigraphy in Congenital Primary Hypothyroidism

The diagnosis on the basis of low serum thyroxine level wiJh high thyrotropin level of congenital pri1111lfY hypothyroidism in newborn screening programs fails to distinguish between transient hypothyroidism and ectopic thyroid, athyrosis, dyshormonogenesis, or transient hyperthyrotropinemill. The correct use of neonotol thyroid scintigraphy aids in making a specific anatomic diagnosis. We scanned 18 of 24 infants who had congenital hypothyroidism detected from screening B6,300 newborn infants, using Tc-99m in the first~ then I-l13 in 1a Eight infants were found to be athyrotic and 2 had ectopic glands; in ~ the thyroid gland appeared normal. Probably due to initiolly poor technique, 1 "othyrotic" infant was later found to be normal. We suggest that before initiating long-term thyroid medication, the specific anatomic and functional diagnosis be confirmed by this low-dose thyroid scintigraphic technique which has been optimi:ud for newborn infants.