Dysfunction of the thyroid gland during amiodarone therapy: a study of 297 cases

Abstract

AimThis study aims to explore and compare the efficacy of radioiodine treatment (RIT) in hyperthyroid and euthyroid patients who have been treated with amiodarone (AM) in the past or are currently undergoing AM treatment. Clinical observation of a group of patients with amiodarone-induced hypothyroidism during a 12-month follow-up period was used for comparison.DesignThis was a observational, two-centered study. Patients were assessed at baseline and at 2 months, 6 months, 8 months, and 12 months after RIT.PatientsGroup A: At baseline (61 males [M] and 17 females [F], mean age 50±19 years), there were 78 euthyroid patients with cardiac arrhythmias, who were treated with AM and developed amiodarone-induced thyrotoxicosis, and currently require retreatment with AM. Group B: Hyperthyroid patients (92 M and 26 F, mean age 72±11.8 years) after AM therapy in the past. Group C: Hyperthyroid patients (66 M and 13 F, mean age 63.9±13.2 years) currently treated by AM. Group D: Hypothyroid patients (6 M and 16 F, mean age 61.4±10.4 years) after AM therapy. The patients from Groups A, B, and C were retreated with AM after ~3–6 weeks of RIT.ResultsIn Group A, after 12 months of RIT therapy, recurrent thyrotoxicosis was observed in six (7.7%) cases, and persistent hypothyroidism was diagnosed in 42 (53.8%) cases. In Group B, hyperthyroidism occurring during treatment with AM was found in 40 (33.9%) patients, and permanent hypothyroidism was observed in eleven (12.5%) cases. After annual follow-up in Group C, nine (11.4%) patients were diagnosed with hypothyroidism, while 27 (34.1%) patients were diagnosed with hyperthyroidism. In Group D, all patients had permanent hypothyroidism and when the concentration of serum thyroid-stimulating hormone was >10 µIU/mL, l-thyroxine was applied.ConclusionOur study showed that radioiodine administration is advisable in certain circumstances, even in euthyroid patients. It allows for continuation of further long-term AM treatment. Additionally, RIT allows for the reintroduction of AM therapy that was previously terminated. Hence, it can help control life-threatening tachyarrhythmias and decrease episodes of thyrotoxicosis.

Amiodarone-Induced Thyroid Dysfunction: A Clinical Update

“…This approach may be justified in patients who are unsuitable for thyroidectomy and need to continue amiodarone therapy [48]. A recent study on 297 patients has shown a benefit of RAI treatment remarkably when amiodarone therapy is continued or needs to be restarted [49]. The study suggested RAI even in euthyroid patients, because it helps continuation, reintroduction and/or adherence to long-term amiodarone treatment.…”

Amiodarone-induced thyroid dysfunction in the developmental period: prenatally, in childhood, and adolescence — case reports and a review of the literature

“…Alternative methods of treatment of AIT (used in adult patients -data supporting usage in paediatric patients are lacking) include: lithium carbonate, radioactive iodine therapy, plasmapheresis, total thyroidectomy, and embolisation of the thyroid artery [18][19][20]. According to the latest recommendations, complete thyroidectomy or radioactive iodine therapy as a radical treatment is indicated in hyperthyroidism, regardless of its type, allowing rapid achievement of euthyreosis and possible re-inclusion of amiodarone into the treatment, especially in type 1 AIT [21,14]. The special role of total thyroidectomy, performed in patients with a severe condition due to cardiac causes and not responding to pharmacological treatment of hyperthyroidism, without first obtaining euthyroidism, is underlined [14].…”

“…However, there are reports in the literature that it is effective and justified not only in cases of normal or increased radioiodine uptake, but also in a situation when radioiodine uptake is lowered [18]. Few data indicate effectiveness of rhTSH-aided radioiodine therapy [4,21]. However, the latest recommendations do not recommend this procedure [14].…”

Landiolol for rate control management of atrial fibrillation in patients with cardiac dysfunction

“…While hyperthyroidism may induce AF, the thyroid gland function is often not known during the first AF presentation, hence amiodarone must be used with caution to prevent a thyrotoxic crisis. 12 …”