Abstract 453: Unmasking true strokes hidden beneath stroke mimics: Simultaneous presentation of Severe Hypothyroidism & Acute ischemic stroke

Introduction Stroke is a leading cause of mortality and morbidity worldwide, and its timely diagnosis and treatment are critical to reducing severe outcomes. Stroke mimics, which include metabolic disorders like hypothyroidism, can complicate diagnosis due to overlapping symptoms. The interplay between hypothyroidism and stroke is complex; hypothyroidism can contribute to the development of stroke, and the physiological stress of an acute stroke can exacerbate hypothyroid symptoms. Severe Hypothyroidism can manifest with neuropsychiatric symptoms such as confusion, lethargy, and cognitive impairment that resemble stroke. Conversely, the physiological stress of an acute stroke can exacerbate hypothyroid symptoms, making differential diagnosis challenging. This case study highlights the complexities in diagnosis and management when both conditions coexist. Case Presentation An 83‐year‐old male with hypertension, chronic kidney disease, status post radio ablation hypothyroidism, and heart failure presented to the emergency department with left‐sided weakness, facial droop, and dysphagia for five days after a ground level fall. Neurological examination showed left‐sided weakness, pronator drift, and slowed speech, with an NIH Stroke Scale (NIHSS) score of 3. CTA on admission showed no acute infarction, but lab results revealed severe hypothyroidism (TSH 79.22 uIU/mL, Free T4 0.25 ng/dL). MRI without contrast identified an acute ischemic infarction in the right corona radiata. Cardiac evaluations, including transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE), and placement of an insertable loop recorder, to rule out a possible cardioembolic source considering the size of infarction (15mm) and patient's risk for occult Atrial fibrillation due to advanced age (>65) and accompanying severe thyroid disease. Results The patient's condition was complicated by the overlap of stroke‐like symptoms due to severe hypothyroidism masking an acute ischemic stroke which was confirmed by a non contrast MRI. Despite negative cardiac imaging findings, the risk of an embolic stroke remained, leading to the placement of an insertable loop recorder to monitor for occult atrial fibrillation. The patient's levothyroxine dosage was increased from 25mcg to 125mcg daily, and he was started on a dual antiplatelet regimen (DAPT) for 21 days, followed by lifelong aspirin therapy. The patient responded to increased levothyroxine dosage with improvement in symptoms, and his stroke management included dual antiplatelet therapy(DAPT) in line with guidelines for minor non‐cardioembolic stroke management. The patient was discharged with instructions for continued neurological and endocrinological follow‐up. Conclusion This case highlights the diagnostic challenges of managing simultaneous severe hypothyroidism and acute ischemic stroke, as the symptoms of each condition can obscure the other. It emphasises the importance of considering stroke mimics in differential diagnoses for suspected stroke and employing a comprehensive, multidisciplinary, and personalized approach to management. This includes thorough evaluation of underlying causes, adherence to evidence‐based guidelines, and careful consideration of the patient's individual risk factors to optimize outcomes and minimize the risk of stroke recurrence.