Changes in radioiodine turnover in patients with autonomous thyroid adenoma treated with percutaneous ethanol injection

In 24 patients with autonomous thyroid adenoma, we studied the hormonal pattern (free thyroxine, free triiodothyronine and thyroid stimulating hormone) and markers of radioiodine turnover before and after nodule ablation with percutaneous ethanol injection. Methods: The hormonal pattern was studied before treatment and at various intervals after nodule ablation. Changes in radioiodine turnover were studied measuring I-131 protein-bound iodine and the biologic half-life of radioiodine in the thyroid (calculated from thyroid uptake at 24 and 48 hr) before and after ethanol treatment. Results: The hormonal pattern was normalized by treatment in all patients and remained normal for the follow-up period. Before treatment, protein-bound I-131 was elevated in all patients but 4; after treatment, it normalized in 15 patients with the disappearance of the adenoma on scintigraphy. In the remaining 9 patients with only partial nodule destruction on scintigraphy, protein-bound I-131 remained elevated although markedly reduced. Biologic half-life was shortened in 18 of 24 patients before treatment; after treatment, it was normal in 18 of 24 patients (13 of 15 with complete nodule ablation and 5 of 9 with partial ablation). Conclusion: Ethanol treatment normalized the hormonal pattern in all patients. Measures of radioiodine turnover were better markers of residual disease in that they normalized in almost all patients with complete nodule ablation, whereas they remained abnormal in a high proportion of patients with incomplete ablation. Thyroid hormones remained normal over a follow-up period of 3-7 yr in all patients.