Isotopic imaging of thyroid ectopia in patients with congenital hypothyroidism

The aim of our studies was to determine the usefulness of various imaging techniques for localization of thyroid ectopia in patients with congenital hypothyroidism (CH). 50 patients with CH were observed. In each case the following studies were performed: serum thyroglobulin level, thyroid radioiodine uptake, scintigraphy using 99mTc and 131I and ultrasonography. Among 50 patients with CH were found: 18 cases (36%) of thyroid agenesis, 7 cases (14%) of thyroid hypoplasia and 25 patients (50%) with lingual thyroid ectopia. Thyroid radioiodine uptake in patients with thyroid ectopia ranged from 2% to 18%, serum thyroglobulin level was from 0.7 ng/ml to 12.8 ng/ml (mean value 6.6 ng/ml). Ultrasonography showed an absence of thyroid gland at its normal site, but its presence in the tongue. Lingual thyroid ectopia was oval or round, and its volume ranged from 0.17 to 1.38 cm3. The use of scintigraphy with 99mTc loads to its accumulation in the submaxillary salivary glands what can make difficult to detect thyroid ectopia. Scintigraphy of the neck and retrosternal area has not shown any thyroid tissue, but there were the accumulation of 131I in thyroid gland in the sublingual area. Conclusions: 1. Thyroid ectopia is a frequent cause of congenital hypothyroidism (in about 50% of all thyroid gland development abnormalities); 2. to detect lingual thyroid ectopia the best method is scintigraphy with 131I and ultrasonography. (author). 13 refs, 5 figs