Dysfunction of the thyroid gland during amiodarone therapy: a study of 297 cases
Authors Czarnywojtek A, Plazinska MT, Zgorzalewicz-Stachowiak M, Wolinski K, Stangierski A, Miechowicz I, Waligorska-Stachura J, Gut P, Krolicki L, Zioncheck M, Ruchala M
Received 18 September 2015
Accepted for publication 14 January 2016
Published 4 April 2016 Volume 2016:12 Pages 505—513
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Dr Hoa Le
Peer reviewer comments 3
Editor who approved publication: Professor Garry Walsh
Agata Czarnywojtek,1,2,* Maria Teresa Płazińska,3,* Małgorzata Zgorzalewicz-Stachowiak,4 Kosma Woliński,1 Adam Stangierski,1 Izabela Miechowicz,5 Joanna Waligórska-Stachura,1 Paweł Gut,1 Leszek Królicki,3 Maja Zioncheck,6 Marek Ruchała1
1Department of Endocrinology, Metabolism and Internal Medicine, 2Department of Pharmacology, Poznan University of Medical Sciences, Poznan, 3Nuclear Medicine Department, Medical University of Warsaw, Warsaw, 4Department of Health Prophylaxis, Laboratory of Medical Electrodiagnostics, 5Department of Computer Science and Statistics, 6Poznan University of Medical Sciences, Poznan, Poland
*These authors contributed equally to this work
Aim: This 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.
Design: This was a observational, two-centered study. Patients were assessed at baseline and at 2 months, 6 months, 8 months, and 12 months after RIT.
Patients: Group 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.
Results: In 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.
Conclusion: Our 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.
Keywords: amiodarone, amiodarone-induced thyrotoxicosis, amiodarone-induced hypothyroidism, radioactive iodine, radioiodine treatment, paroxysmal atrial fibrillation, ventricular tachycardia
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