7165 A Case of Severe Myxedema Coma with Levothyroxine Allergy

Abstract Disclosure: A. Rothstein Costris: None. A. Yaseen: None. S. Levy: None. Introduction: Myxedema coma is a life threatening condition with a mortality rate of 25-60%. Untreated, it can lead to fatal physiological changes. The treatment is thyroid hormone replacement therapy, alongside supportive care for complications. Clinical Case: A 65-year-old woman, who has been dealing with untreated hypothyroidism since 2012 and reported allergies to various levothyroxine brands, presented with falls, weakness, and exacerbated leg numbness. During the examination, she exhibited periorbital edema, non-pitting edema in the lower extremities, bradycardia, and hypothermia. The blood work revealed an elevation in TSH levels at 301 uIU/L (0.45-5.33 uIU/mL). The patient was administered IV Synthroid (200 mcg), Atropine, and Hydrocortisone due to concerns about myxedema coma. After four hours, the patient experienced angioedema and hypotension, necessitating intubation. This situation was complicated by a pulseless electrical activity (PEA) arrest. Following cardiopulmonary resuscitation and the administration of epinephrine, the patient achieved return of spontaneous circulation. The allergy team assessed the patient for potential anaphylactic shock from IV Synthroid. Subsequently, the patient was initiated onIV Liothyronine and Hydrocortisone, leading to improvement in mental status over a period of a few weeks, and no adverse effects were reported. Thyroid labs improved to TSH of 53 (0.45-5.33 uIU/mL), FT3 of 3.3 (2.5-4.4 pg/mL) and total T3 of 133 (87-178 ng/dl). Upon discharge, the patient was prescribed Liothyronine, with plans to perform a Levothyroxine desensitization test in the outpatient setting. Conclusion: Myxedema coma is an endocrine emergency. Patients usually present with deteriorating mental status, hypothermia, and multiple organ system abnormalities. The diagnosis relies more on the clinical presentation and physical examination than on laboratory results. Thyroid replacement therapy serves as the cornerstone of treatment, with a preference for T4 due to its greater availability and lower likelihood of adverse events compared to Liothyronine, which may increase the risk of mortality at higher doses. Despite associated risks, incorporating low doses of Liothyronine is still considered in treatment plans, driven by concerns about reduced T4 to T3 conversion in myxedema patients. Hypersensitivity reactions to Levothyroxine are uncommon but may manifest as widespread hives, swelling, eczema-like skin rashes, elevated body temperature, and compromised liver function, with only one case reporting an anaphylactic reaction to Levothyroxine. In summary, the potential for experiencing an anaphylactic reaction to Levothyroxine exists, highlighting the need to contemplate alternative treatments, such as Liothyronine. Desensitization methods can be considered once the patient's condition is stable. Presentation: 6/2/2024