Increased uptake of iodine-131 in metastases of differentiated thyroid carcinoma associated with less severe hypothyroidism following total thyroidectomy.

Background. In an attempt to determine possible factors affecting the efficacy of iodine-131 (I-131) treatment for metastatic thyroid carcinoma, the authors focused their efforts on thyroid functions after total thyroidectomy. Methods. Between 1980 and 1991, 47 patients with lung metastases of differentiated thyroid carcinoma were treated with I-131. Relationships of the images on post-therapy scans with various clinical features were studied. Results. Among them, 28 (59.6%) showed I-131 uptake in the metastases on post-therapy scans. Younger patients had lesions that concentrated more radioactive iodine than did those of older patients