Endocrine Abstracts

Background: Hyperthyroidism caused by autonomous functioning thyroid nodules (ATN) is usually treated with I-131. Recently, radiofrequency ablation (RFA) has emerged as a promising alternative but it is not yet incorporated in guidelines.

Aims: Assessment of efficacy of RFA treatment in patients with hyperthyroidism caused by ATN and factors that may affect treatment success.

Methods: Retrospective analysis of patients treated for hyperthyroidism caused by ATN with RFA, when follow-up of at least one year was available. Results of patients with a single toxic adenoma (STA) are compared with patients with a toxic multinodular goitre (TMG) and a dominant hyperactive nodule on scintigraphy and ultrasound. Proportions were compared by the chi-squared test. Cure was defined as thyroid medication-free biochemical euthyroidism.

Results: 48 patients (36 STA, 12 TMG) were included, 85% were female, mean age was 55 (range 27-80). The median nodule volume was 12 ml at baseline. Median energy delivered during RFA was 0.6 kCal/ml. One year post RFA 29 patients (60.4%) were cured after a median of 3.2 months (range 0.1-11). Median volume reduction was 68% (range 21-99). One patient, with a history of hemithyroidectomy, developed hypothyroidism. 18 patients (37.5%) were hyperthyroid one year post RFA. Baseline and RFA parameters were similar for STA and TMG patients. The one-year cure rate was higher among STA patients compared to TMG: 72% vs 25% (P<0.05), respectively. 13 patients with persistent hyperthyroidism received re-RFA. 9 (69%) of them were cured at last follow-up (median 12 months post re-RFA). Extended follow-up was available for 31 patients (25 STA and 6 TMG). 3 STA and 1 TMG patients developed late recurrent hyperthyroidism between 24-37 months post-RFA. Of all 48 patients, cure was achieved in 86% of STA patients and in 33% of TMG patients after 1 or 2 RFA sessions at last available follow-up after first intervention (median 20 months after first intervention).

Conclusion and discussion: The efficacy of single session RFA session was nearly 3 times higher in STA patients compared to TMG. These data confirm that RFA is an effective treatment for STA. Further analysis is required to assess the role of RFA in TMG. Follow-up after RFA should be at least 2 years since late recurrences are observed.