Amiodarone-Induced Thyrotoxicosis and Clinical Risk Factors for Thyrotoxic Crisis

Abstract Background Amiodarone-induced thyrotoxicosis (AIT) is a serious complication of long-term amiodarone therapy. Its most severe manifestation is thyrotoxic crisis (TxC), a rare but life-threatening condition. Aim To analyze patients with AIT, identify demographic and clinical parameters, evaluate diagnostic and therapeutic approaches, and determine predictive risk factors for TxC. Methods A retrospective study of 55 consecutive patients with confirmed AIT followed between 2005 and 2024. Baseline characteristics, laboratory findings, thyroid ultrasound, clinical presentation, therapy and outcomes were analyzed. Patients were classified into AIT type 1, type 2, or mixed type. TxC was diagnosed using the Burch–Wartofsky scoring system. Results The cohort comprised 45 men (82%) and 10 women (18%) with a mean age of 62.3 ± 9.9 years. Amiodarone was most commonly prescribed for atrial fibrillation (78%), and the mean duration of therapy before AIT onset was 988 ± 502 days. Mean fT4 at diagnosis was 43.2 ± 18.3 pmol/L and mean TSH 0.017 ± 0.052 mIU/L. AIT type 1 was identified in 23%, type 2 in 44%, and mixed type in 33% of patients. TxC developed in 6 patients (11%). These patients were all men, had higher maximum fT4 levels (> 74.5 pmol/L) and larger thyroid volume (> 19 mL), and urgent thyroidectomy was required in 5 cases. Conclusion TxC occurred in 11% of patients with AIT and was associated with higher thyroid hormone levels and larger thyroid volume. Early recognition and interdisciplinary management are essential for improving outcomes.