In vivo isotope study of the thyroid with 99mTcO4- in neonatal congenital hypothyroidism.

Seventeen patients, screened from a neonatal programme for hypothyroidism were studied. As well as the scintigraphic investigations, serum TSH, T3, free T3, T4, free T4, and TBG were measured in all patients. Not more than 11.1 MBq (300 microCi) 99mTcO4- was administered IV. A gamma camera with a parallel-hole collimator on line with the computer was used. The method allowed good statistics to be obtained in 5-10 min in a wide field of exploration, thus reducing the problems of positioning and prolonged immobilization of the young patient. The data collected in the computer were elaborated to define better the characteristics of the thyroid image. This kind of in vivo study introduced into a screening programme, enables an 'anatomic' diagnosis of the defect to be obtained before starting the therapy. This is undoubtedly valuable from the epidemiological point of view, enables early determination of the degree of thyroid insufficiency, and contributes to the formulation of a prognosis based on the degree and on the moment in which prenatal harm occurred.