(123)IODINE SCINTIGRAPHY AND PERCHLORATE DISCHARGE TEST IN THE DIAGNOSIS OF CONGENITAL HYPOTHYROIDISM

Aim: Thirty eight children suffering from congenital primary permanent hypothyroidism were studied to determine the diagnostic impact of I-1 23 scintigraphy in comparison to labaratory findings and ultrasonograp hy. Methods: In all patients I-123 scintigraphy was performed after in travenous administration of 3.7 MBq I-123. If accumulation of the radi otracer in thyroid tissue occured a perchlorate discharge test was per formed subsequently. Results: Scintigraphy revealed athyrosis in 7 chi ldren. In 9 children a lingual thyroid was observed. Deficiency in iod ine organification was diagnosed by a significant discharge of I-123 i n 15 patients. In four of these children the diagnosis of Pendred's sy ndrome could be established. Ectopic thyroid tissue could be demonstra ted only by scintigraphy where clinical examination and sonography fai led in the diagnosis in all cases. Hypoplasia of the thyroid gland as it was diagnosed in 2 cases by ultrasonography appeared to be unlikely because a normal I-123 uptake was seen in these patients. In 2 patien ts with scintigraphic proven athyrosis an orthotopic gland had been fa lsely considered by ultrasound. In 44% of our patients the final diagn osis could only be established if I-123 scintigraphy and perchlorate d ischarge test were performed. Conclusion: This findings suggest that s cintigraphy is indispensible in the correct diagnostic work up of cong enital hypothyroidism.