Endocrine Abstracts

Objective: To assess the outcome of medical and ablative therapies in amiodarone-induced thyrotoxicosis (AIT).

Subjects and methods: Seventy patients (32 M/38 F, aged 59.7±1.4 years) with AIT (24-type 1, 20-type 2 and 26-mixed forms) were followed-up 13.4±2.3 months. TSH was measured by immunoradiometric assay, TT₃ and TT₄ by chemiluminescence.

Results: Antithyroid drugs (ATD) were used as single therapy in 44 patients and combined with glucocorticoids in 22 patients. Glucocorticoids were used in monotherapy in 3 patients. Mean duration of treatment was 9.1±1 months for ATD and 2.1±0.2 months for glucocorticoids. Radioiodine was administered in 9 patients and thyroidectomy was performed in 4 patients. Amiodarone was withdrawn in 66 patients (94.3%). TSH normalized in 5.7±0.5 months, and T₃ and T₄ in 3.8±0.4 months under ATD and/or glucocorticoids.

Thyrotoxicosis control was noticed in 17/24 patients with type 1 AIT: after 8.1±0.5 months of ATD (n=7), after ATD+radioiodine (n=6) and after ATD+thyroidectomy (n=4). Seven patients received ATD for less than 3 months. Thyrotoxicosis control was noticed in 15/20 patients with type 2 AIT: after ATD and/or glucocorticoids (n=14, mean period 5.3±1.1 months) or spontaneously after amiodarone withdrawal (n=1, subclinical AIT); 5 patients received ATD+glucocorticoids for less than 3 months. Thyrotoxicosis control was noticed in 10/26 patients with mixed type AIT, treated 11.8±3.4 months; 3 patients developed hypothyroidism after radioiodine; 13 patients are still on therapy.

Medical treatment duration was significantly longer in type 1 and mixed type AIT as compared with type 2 AIT, P=0.04, t test. Remission rate was similar in type 1 after medical and ablative therapy (17/24 patients, 70.8%) and in type 2 AIT after ATD and/or corticotherapy (15/20 patients, 75%), P=0.7, χ² test. One patient died despite FT₄ normalization on ATD+glucocorticoids.

Conclusions: Combined medical and ablative therapies were effective in most patients with AIT, decreasing mortality rate.