Introduction: Amiodarone induced thyrotoxicosis (AIT) remains a diagnostic and therapeutic challenge. Broadly, AIT is classified as type 1 (underlying latent thyroid disorder) or type 2 (destructive thyroiditis). Despite being an on-going clinical conundrum, there is no U.K. wide guidance on management of AIT. We report a retrospective review of recent cases treated within our department as AIT.
Methods: Data was collected for all patients referred to our tertiary endocrine unit with suspected AIT during 2010 to 2014. The review primarily focussed on duration of Amiodarone therapy, type of AIT, thyroid peroxidase antibody status and time to remission of AIT. A total of thirty nine patients were referred to our unit with AIT, within this period. Out of these, six have been excluded so far, due to incomplete data.
Results: A total of 33 patients were included in the review. The average age of patients referred with AIT was 66 years (range 3081years), predominantly being men (79%). The average duration of Amiodarone therapy prior to diagnosis of AIT was 45 months (range 8132 months). TPO status was assessed in 82% of patients out of whom 11% were TPO positive. Majority of patients were classed as type 2 AIT (64%) by the treating clinician. Following diagnosis, Amiodarone was discontinued amongst 85% of the patients. In terms of treatment, 30 patients were commenced on Carbimazole (91%) out of which 47% were rendered euthyroid with carbimazole only. Out of 53% that received Carbimazole and Prednisolone therapy, only two were referred for thyroidectomy. Three patients (9%) remitted during watch and wait period. One patient required elective radioiodine in addition to medical treatment. The average time to remission was 2.9 months (range 3 weeks to 6 months).Remission period of AIT was similar in those who discontinued versus who continued Amiodarone therapy (2.8 vs 3 months).
Conclusion: In the absence of clear guidelines for classification and management of both types of AIT, overall practise remains primarily determined by individual clinicians experience. This has been highlighted in surveys undertaken by both the European Thyroid association and within the United Kingdom. Our review further highlights differences in practise amongst endocrinologists in management of AIT. This is particularly true in relation to diagnostic workup as well as management strategies.