SAT-583 Expanding the Clinical Spectrum of Hashimoto's Thyroiditis: Acute Presentation of a Chronic Illness

BACKGROUND: Hashimoto’s encephalopathy is an entity poorly defined in the pediatric literature , with widely variable presentations ranging from acute to chronic symptoms. Most cases described are of older adults, with female predominance and generally with previously diagnosed autoimmune thyroiditis. We describe a previously healthy adolescent male who presented in an acute encephalopathic state and was found to be frankly hypothyroid with positive thyroid peroxidase antibodies consistent with Hashimoto’s encephalopathy. CASE DESCRIPTION: A 16 year old previously healthy male presented with unresponsiveness to the emergency room. He underwent an extensive metabolic and infectious work up which was negative. Vital signs were normal throughout his hospital course. A TSH was ordered as part of the work up for altered mental status and was found to be significantly elevated at 492 mcIU/ml . Free T4 and free T3 levels were also low at 0.5 ng/dl (0.8-1.8 ng/dl) and 1.5 pg/ml (2.3 - 4.2 pg/ml) respectively. TPO antibody titer was >1000 IU/mL. Family reported no previous signs or symptoms suggestive of hypothyroidism. CSF autoimmune/paraneoplastic panel was negative. He was initiated on Levothyroxine with an intravenous loading dose. The following day, he also received methylprednisolone 150 mg I.V daily for 3 days. Clinically, he was back to baseline 48 hrs after initiating levothyroxine. He was discharged home on levothyroxine supplementation. CONCLUSION: Hashimoto’s encephalopathy is a controversial entity, with some authors recommending that the term ‘steroid responsive encephalopathy’ be used to describe patients presenting in an encephalopathic state, found to have positive thyroid peroxidase antibodies and respond to high dose steroids. Our patient showed clinical improvement within 24 hours of initiating levothyroxine. Although autoimmune thyroiditis with hypothyroidism typically has a gradual onset with long standing symptoms, it should be ruled out even in acute encephalopathic presentations. While the role of autoantibodies in the pathophysiology of Hashimoto’s or steroid responsive encephalopathy remains uncertain, this case highlights the importance of a high index of suspicion for thyroid dysfunction when evaluating patients with acute mental status changes.