Endocrine Abstracts

Background: Amiodarone induced thyrotoxicosis (AIT) is a potentially catastrophic situation for patients with cardiac disease who are at risk of life-threatening complications. We describe the protracted and challenging journey of a patient with Laminopathy and a significant cardiac history who developed AIT.

Clinical Case: A 53-year-old man was referred with thyrotoxicosis (TSH <0.01mU/l, free T4 61 pmol/l, free T3 8.0 pmol/l) detected following commencement of amiodarone for atrial fibrillation. He had a history of laminopathy (due to LMNA mutation), associated cardiomyopathy and intractable arrhythmia, requiring ICD insertion, atrial and ventricular ablations. Medications included Amiodarone, Mexiletine, Bumetanide, Eplerenone, Bisoprolol, Entresto, Rivaroxaban, and Empagliflozin. Laminopathy was present in numerous relatives, including his mother, who had a history of AIT also. TRAb antibody was <0.8 IU/l. An ultrasound thyroid showed normal sized gland, mildly heterogenous echogenicity and reduced vascularity. He was treated with carbimazole and dexamethasone for AIT but remained thyrotoxic, and developed cardiac decompensation (oedema, SOB) with early myopathy. Second line agents cholestyramine and iodine solution were added, without effect. It was decided that he required salvage thyroidectomy, and he underwent numerous plasma exchanges in preparation for surgery. Following thyroidectomy, the patient recovered well. His thyroid and cardiac symptoms improved, and he was discharged on Eltroxin with follow up.

Conclusion: We describe a rare case of treatment resistant AIT. The case was complicated by the underlying laminopathy, which further increases the risk of myopathy, cardiac arrhythmia and cardiac decompensation in a thyrotoxic patient. Prompt recognition of treatment resistance is required, because the window of opportunity for safe thyroidectomy in such patients is narrow. Options for rendering patients euthyroid in resistant AIT include perchlorate, iopanoic acid, and therapeutic plasma exchange.