MON-448 Myxedema Coma Masked by Dementia

Abstract Disclosure: K. Ho: None. E. Kabaswaga: None. K. Cano: None. J. Baskaran: None. Myxedema coma is a medical emergency with a high mortality rate that can result from poorly managed hypothyroidism. It can be challenging to manage when there are confounding factors. We report a case of a 68-year-old male to highlight the importance of prompt diagnosis and intervention. A 68-year-old man presented due to altered mental status and seizure-like activity. His past medical history included hypothyroidism and Parkinson’s disease with dementia. He was hypotensive, bradycardic, hypothermic, and observed to have a grand mal seizure in the hospital. TSH was 134 and free T4 was 0.19. A score of 80 on the diagnostic scale for myxedema coma confirmed the diagnosis. He was taken to the ICU, intubated, and started on vasopressors for his sepsis, as well as intravenous levothyroxine and hydrocortisone. Steroids were tapered once hemodynamically stable and adrenal insufficiency was ruled out. Neurology was consulted for new-onset seizures, with an EEG showing signs of a focal seizure. Vitals gradually normalized; IV levothyroxine was transitioned to a stable oral dose. He was discharged with new antiepileptic medication and optimized hypothyroidism medication. In this case, the diagnosis was confounded by the patient’s underlying dementia and abnormal movements, which could have been used to explain the patient’s general obtundation to be signs of his Parkinson’s. Due to his known hypothyroidism, clinical suspicion remained high for myxedema with seizures as a complication. Subsequently, the patient was managed appropriately with medication and consultation with neurology. Levothyroxine is the drug of choice since it has a slow onset and fewer side effects than T3, which is more potent, but can increase tissue oxygen consumption and strain the cardiovascular system, making it risky for elderly patients. TSH levels reflect the thyroid status over 6 weeks, thus response to therapy is determined by T4 levels, and clinical status. This case underscores the importance of quickly identifying and treating myxedema coma in patients, especially in those with confounding diagnoses, to improve outcomes. Myxedema coma has an estimated annual incidence of 0.22 cases per million in the United States. Although uncommon, it carries a high mortality rate ranging from 30% to 60%. It frequently manifests in individuals with untreated hypothyroidism and is commonly precipitated by a systemic illness with broad symptoms, which require elucidation to separate from confounding factors. Our patient developed myxedema due to his noncompliance with medications, with underlying Parkinson’s disease and dementia muddling the diagnosis, but after diagnosis, eventual management was successful. This case emphasizes the importance of quickly identifying and treating myxedema coma in patients, especially in those with confounding diagnoses, to improve outcomes. Presentation: Monday, July 14, 2025