Endocrine Abstracts

Background: Amiodarone is an antiarrhytmic drug used mainly in atrial fibrillation. Amiodarone-induced thyrotoxicosis (AIT) is less common than hypothyroidism, but it represents a true therapeutic challenge. AIT can be due iodine load (type 1) or a destructive thyroiditis (type 2).

Methods: Retrospective study of patients with AIT, diagnosed between 2010 and 2015, in a central hospital. We reviewed medical records regarding age, gender, amiodarone therapy, hospitalizations, cardiovascular events, thyroid function and therapy. We used descriptive statistics, t-test for continuous variables and chi-squared distribution for categorical variables.

Results: We identified 40 patients with AIT (n=40): 15% were type 1, 62.5% type 2 and 22.5% mixed or undefined forms. Mean age of presentation was 71.1±9.7 years, with an equal distribution of gender. 47.5% were managed as inpatients, mainly due worsening of atrial fibrillation or cardiac insufficiency, with higher FT4 levels (P=0.014). All patients stopped Amiodarone after the diagnose, however 25% stopped this drug before the appearance of AIT, with a maximum of 11 months between them. Most patients had TSH suppressed, with a mean FT4 level of 46 pmol/l and FT3 of 10.6 pmol/l. Thyroid anticorps were more prevalent in type 1 TIA (P<0.001). Methimazole was used in 85% of the patients, 52.5% did Prednisolone and 15% of cases were transient without treatment. Treatment duration mean was 11.5 months (2 – 48), statistically significantly higher in type 1 vs type 2 (P<0.001). A total of 10 cardiovascular events after the beginning of AIT treatment, with another hospitalization needed. 3 patients died, 2 of them due to the thyroid disfunction.

Conclusion: AIT is a concern in elderly people, because treatment is challenging. Patients treated with Amiodarona and AIT need frequent hospitalizations. Type 2 AIT was the most frequent (62.5%), with higher FT4 (P=0.014), but treatment duration was smaller (P<0.001).