Endocrine Abstracts

Introduction: Myxedema coma is the most serious manifestation of hypothyroidism and, although rare, it is associated with high mortality. Amiodarone therapy can lead to thyroid dysfunction, either hyperthyroidism or hypothyroidism; however, in this context, myxedema coma is rare. Amiodarone discontinuance is not recommended in hypothyroidism’s treatment, but may lead to its resolution if there is no pre-existing thyroid pathology. We present a clinical case of amiodarone-induced hypothyroidism meeting myxedema coma criteria, reverted to euthyroidism after drug suspension.

Clinical Case: Female, 76 years-old, history of valvular heart disease and atrial fibrillation (AF) treated with amiodarone since 2012. Admitted to the emergency department on 02/2021 presenting with lethargy, dyspnea, orthopnea and peripheral edema. Physical examination revealed hypothermia (34°C), bradycardia (45 bpm), hypotension (88/58 mmHg) and anasarca. Additionally, the presence of type 2 respiratory failure, acute kidney injury (creatinine 3.17 mg/dl), hyponatremia (127 mmol/l), hyperkalaemia (5.74 mmol/l) and AF with slow ventricular response was documented. Under the suspicion of myxedema coma (Popoveniuc score 90 points) thyroid function was assessed, which confirmed the presence of hypothyroidism: TSH 71 uUI/ml (0.30-3.94), T4L 0.42 ng/dl (0.95-1.57) and T3L 1.10 ng/ml (0.78-1.90), with negative thyroid autoimmunity. The patient was diagnosed with severe hypothyroidism meeting myxedema coma criteria, associated with neurological, cardiovascular, respiratory and renal dysfunctions. Levothyroxine therapy was iniciated (200 μg loading dose, followed by IV 100 μg/daily), associated with IV hydrocortisone 100 mg (until adrenal insufficiency was excluded), furosemide and non-invasive ventilation. The patient presented favorable evolution with resolution of all dysfunctions, being discharged under 150 μg levothyroxine and bisoprolol 1.25 mg instead of amiodarone, according to Cardiology recommendations. In outpatient consultations, thyroid ultrasound was performed revealing no changes, supporting amiodarone-induced hypothyroidism. Subsequent assessments documented progressively lower levothyroxine needs leading to its discontinuance on 04/2022, with the patient presenting clinically and analytically euthyroid since then.

Discussion: Amiodarone-induced hypothyroidism can occur in up to 30% of patients undergoing this therapy, which can lead to the development of myxedema coma in extreme situations, especially when its diagnosis is not carried out in a timely manner. Discontinuation of amiodarone in cases of hypothyroidism is not indicated; however, if performed, it may induce hypothyroidism’s resolution.