Incidence of amiodarone-induced thyroid dysfunction in Korean

Jin, Seung Won; Yoon, Hee Jeoung; Lee, Jong Min; Oh, Yong Seok; Lee, Man Young; Rho, Tai Ho; Chae, Jang Sung; Kim, Jae Hyung; Choi, Kyu Bo; Hong, Soon Jo

Abstract

BACKGROUND: Amiodarone is an effective antiarrhythmic agent, but it is used restrictively due to several side effects. Amiodarone has been caused thyroid dysfunction, thyroid hyperfunction or hypofunction in several clinical studies. In this study, we assessed the clinical features, frequency and nature of thyroid dysfunction in patients with amiodarone therapy
METHODS
A total of 150 patients (Male;n=71, Female;n=79) was assessed. They had never had the history of thyroid disease and had been received amiodarone therapy. All the patient's medical records on therapeutic dose and duration, body weight, height, body mass index and thyroid function test were reviewed. Patient's underlying diseases were supraventricular arrhythmia (n=54) and ventricular arrhythmia (n=96). The dose of amiodarone was between 100 mg and 400 mg, and the mean duration of therapy was 36 months. We defined decreased TSH with elevated T3 and T4 as thyrotoxicosis, and elevated TSH as hypothyroidism
RESULTS
Thyroid dysfunction was observed in 56 (37.3%) patients and their mean body mass index (BMI) was 23.6 kg/m2. Of them, thyrotoxicosis and hypothyroidism were observed in 5 (3.3%) patients and 51 (34%) patients, respectively. The difference of sex in hypothyroidism was almost not visible (male;n=24, female;n=27), also the correlation with BMI and thyroid function was not (mean BMI=23.7 kg/m2). Amiodarone was maintained for 46 months in hypothyroidism patients, that was more longer duration than normal thyroid patients (30 months).
CONCLUSION
In korean patients with amiodarone therapy, one third patients presented thyroid dysfunction and most of them were hypothyroidism. No correlation was found between thyroid dysfunction and sex and BMI. Hypothyroidism prevalances in patients with long duration of amiodarone therapy, but high dose therapy may induce thyrotoxicosis.