Amiodarone-Induced Thyrotoxicosis, Risk Factors and Predictors of Outcome: A Retrospective Study

Background Amiodarone induced thyrotoxicosis (AIT) is not uncommon and is often associated with significant morbidity and mortality. Factors that predict poor prognosis in AIT have not yet been sufficiently investigated. Objective: To examine the characteristics and short-term clinical outcomes of patients with AIT (up to six months from diagnosis). We evaluated the relationship between T3 and T4 levels at the time of presentation and complications associated with AIT. Methods: A retrospective epidemiological study on patients admitted to Carmel Medical Center between the years 2004-2018. We reviewed electronic medical records of patients who bear the diagnosis of thyrotoxicosis and consumed amiodarone. Demographic and clinical characteristics of patients that develop AIT were evaluated. We evaluated the association between T3 and T4 levels at the time of presentation a poor prognosis. Three primary outcomes were defined: 1. Mortality. 2. Development of AIT-related complications that required hospitalization. 3. The need for thyroidectomy. Results: 400 patients bear a diagnosis of thyrotoxicosis and consumed amiodarone. However, only 39 patients met the full definition of AIT. The composite outcome of mortality, AIT-related complications and thyroidectomy was achieved in the vast majority of patients (94.8%, 37 out of 39 participants). Three patients (7.6%) died, 35 (89.7%) were hospitalized with AIT-related complications and 8 (20.5%) required thyroidectomy. There was a statistically significant relationship between high T4 levels and the composite of two main endpoints: mortality and the need for thyroidectomy in the first half year of diagnosis (P=0.009). Conclusions: AIT is associated with significant morbidity and mortality. An elevated level of free T4 reflects the severity of AIT. In patients with significantly increased T4 values, an early surgical intervention should be considered.