[123I-scintigraphy and perchlorate depletion 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 123I scintigraphy in comparison to laboratory findings and ultrasonography.

METHODS

In all patients 123I scintigraphy was performed after intravenous administration of 3.7 MBq 123I. If accumulation of the radiotracer in thyroid tissue occurred a perchlorate discharge test was performed subsequently.

RESULTS

Scintigraphy revealed athyrosis in 7 children. In 9 children a lingual thyroid was observed. Deficiency in iodine organification was diagnosed by a significant discharge of 123I in 15 patients. In four of these children the diagnosis of Pendred's syndrome could be established. Ectopic thyroid tissue could be demonstrated only by scintigraphy where clinical examination and sonography failed 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 123I uptake was seen in these patients. In 2 patients with scintigraphic proven athyrosis an orthotopic gland had been falsely considered by ultrasound. In 44% of our patients the final diagnosis could only be established if 123I scintigraphy and perchlorate discharge test were performed.

CONCLUSION

This findings suggest that scintigraphy is indispensible in the correct diagnostic work up of congenital hypothyroidism.