SAT-609 Plasmapheresis as Salvage Treatment in a Patient with Amiodarone-Associated Thyroid Dysfunction

Introduction: Treatment with amiodarone is associated with thyroid dysfunction. Thyrotoxicosis is a possible consequence and 3 types of amiodarone-induced thyrotoxicosis (AIT) are commonly defined: AIT1 (Iodine-induced hyperthyroidism), AIT2 (hyperthyroidism resulting from destructive thyroiditis) and mixed/indefinite forms resulting from a mixture of types 1 and 2. Treatment consists of thionamides or glucocorticoids, depending on the AIT type. Subsequently, thyroidectomy should be considered. Plasmapheresis has been mentioned as a "life-saving" treatment, although its use is not yet a standard practice in the resolution of thyrotoxicosis. Case report: 61-year-old man, with history of NYHA class II/III ischemic heart failure, submitted to cardiac resynchronization therapy defibrillator in 2014, permanent atrial fibrillation, dyslipidaemia, ex-smoker and COPD. No history of thyroid pathology. His usual medication included amiodarone 200mg od. On February of 2018, the patient entered the emergency room due to anginal pain that developed for cardiorespiratory arrest (CRA) and reverted after cardioversion. He was admitted to the Coronary Unit where an analytical study showed TSH - 0.01 μUI/mL, FT4-4.21ng/dL. Endocrinology evaluation was requested. The patient presented with digital tremor, without exophthalmia and a nodule was perceptible on palpation. It was prescribed thiamazole 30mg/day because of the suspicion of AIT 1. He performed thyroid ultrasonography with doppler that showed isoechoic nodule of 14mm in the right lobe, aspects suggestive of thyroiditis and preserved vascularization of the gland. Anti-thyroid and anti-TSH receptor antibodies were absent. Thus, the hypothesis of AIT 2 was more likely to occur and prednisolone 20mg/day was added, aiming to achieve euthyroidism that would provide the necessary conditions for the patient to undergo total thyroidectomy. From this moment on, FT4 and TSH assays were repeated every 3 days and prednisolone and thiamazole doses were increased to a maximum of 70mg and 40mg, respectively. Approximately 50 days after the onset of hospitalization, due to the inability to achieve euthyroidism and also to the progression of the heart disease that motivated a new CRA during the admission, total thyroidectomy was mandatory and therefore it was decided to proceed to plasmapheresis. The procedure went without any harm and a FT4 of 1,82 ng/dL was reached. This value was above the reference range, however with a marked improvement compared to the value prior to the procedure. The patient was then submitted to total thyroidectomy but died 2 days later due to multiorganic dysfunction. Conclusion: This case shows the difficulties that are often found in the treatment of AIT. Still, it makes clear that in urgent cases, plasmapheresis can be a viable and effective alternative in the restoration of euthyroidism, with the potential to save lifes.