MON-452 - Amiodarone-Induced Myxedema Coma Presenting with Profound Bradycardia and Acute Renal Failure in an Elderly Woman: A Rare, Life-Threatening Complication

Introduction:
Myxedema coma is an uncommon complication of severe hypothyroidism. Amiodarone-induced hypothyroidism (AIH) is relatively frequent, but progression to myxedema coma is exceptionally rare, particularly with rapid onset.

Case Description:
A 78-year-old woman with history of type 2 diabetes, chronic kidney disease stage 4, iron deficiency anemia, hyperlipidemia, hypertension, depression, atrial fibrillation, coronary artery disease, and prior transcatheter aortic valve replacement presented with progressive weakness, recurrent falls, and confusion three months after starting amiodarone for atrial fibrillation. She was hypothermic, bradycardic, and hypotensive, with laboratory evidence of profound hypothyroidism (TSH 287 μIU/mL, free T4 < 0.11 ng/dL) and acute-on-chronic kidney injury (creatinine 6.0 mg/dL). Bradycardia was refractory to atropine, requiring dopamine infusion. She developed respiratory failure necessitating intubation. Management included immediate discontinuation of amiodarone, intravenous levothyroxine, empiric hydrocortisone, and comprehensive supportive care. She improved hemodynamically and neurologically, was extubated, and discharged to inpatient rehabilitation.

Discussion:
This case highlights rapid-onset myxedema coma secondary to amiodarone-induced hypothyroidism, occurring within three months of therapy—earlier than most reports, with < 25 cases worldwide. Amiodarone’s large iodine load and inhibition of peripheral T4-to-T3 conversion can precipitate profound hypothyroidism even without pre-existing thyroid disease. Prompt recognition, drug discontinuation, thyroid hormone replacement, and glucocorticoid coverage are lifesaving.

Conclusion:
Clinicians should maintain vigilance for early thyroid dysfunction in amiodarone-treated patients. Baseline and frequent thyroid monitoring—at one- and three-months post-initiation, then every six months—may enable timely diagnosis and prevent fatal myxedema coma.

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