SAT-624 Amiodarone-Induced Myxedema Coma

Abstract

Introduction Myxedema coma is an endocrine emergency. It is characterized by severe hypothyroidism resulting in altered mental status, bradycardia, and hypothermia. Hyponatremia, hypoglycemia, and hypoventilation may also be seen. Hypothyroidism is diagnosed with high serum TSH and low free T4 levels. Amiodarone is a commonly used medication used for treatment of arrhythmias including atrial fibrillation. However, amiodarone is associated with many adverse effects including thyroid dysfunction. Amiodarone use may result in both hypothyroidism and hyperthyroidism. Clinical Case Patient is a 69-year-old male presenting with altered mental status. Patient was noted to have fingerstick glucose of 45 mg/dL without prior history of diabetes. Hypoglycemia was corrected without change in mental status. Vital signs were notable for temperature 96oF and heart rate 64. On physical examination, patient noted to be lethargic and euvolemic. Laboratory workup was notable for sodium 107 mEq/L and normal creatinine, with last known sodium value of 135 mEq/L. Patient was initiated on hypertonic saline and admitted to the intensive care unit. Patient’s history was notable for persistent atrial fibrillation for which amiodarone was initiated one year prior. Patient had no previous history of thyroid surgery or radioiodine therapy. Laboratory workup revealed normal serum osmolality, urine sodium 64, and urine osmolality 518. Therapy with IV levothyroxine and stress-dose glucocorticoids were initiated while additional laboratory workup was pending. Labs revealed morning cortisol 14 ug/dL, TSH 44 uIU/mL, free T4 0.35 ng/dL, and total T3 0.34 ng/mL. IV levothyroxine was continued with return of mental status to normal. Thyroid peroxidase antibody was negative. Sodium was monitored frequently and normalized with thyroid hormone replacement. Serum TSH and free T4 improved. After consultation with cardiology, patient’s amiodarone was discontinued. Patient was transitioned to oral levothyroxine. Discussion Amiodarone use is associated with many adverse effects including hypothyroidism. However, myxedema coma in association with amiodarone has been infrequently reported in the literature. Hypothyroidism has been reported to develop up to 39 months after initiation of amiodarone. In our patient, severe hypothyroidism developed 12 months after starting amiodarone. When there is a high index of suspicion, serum TSH, free T4, and cortisol should be obtained. Cortisol is checked to assess for concomitant adrenal insufficiency. Treatment with thyroid hormone replacement and stress-dose steroids should be initiated without delay while laboratory tests are pending. Patient’s thyroid function, serum sodium, and mental status will normalize with thyroid hormone replacement. The decision to continue or discontinue amiodarone should be made in consultation with a cardiologist.