Case Report Encephalopathy associated with autoimmune thyroid disease (Hashimoto's thyroiditis) presenting as depression: a case report ☆ Chao-Yu Liu, M.D. a , Mei-Chih Meg Tseng, M.D., M.Sc. a,b, ⁎ , Po-Hsien Lin, M.D. a a Department of Psychiatry, National Taiwan University Hospital, Taipei, 10002, Taiwan b Department of Psychiatry, National Taiwan University College of Medicine, Taipei, 10051, Taiwan Received 25 February 2011; accepted 27 May 2011 Abstract Encephalopathy associated with autoimmune thyroid disease (EAATD) is a rare condition associated with Hashimoto's thyroiditis or Graves' disease. It is often underdiagnosed because of the various clinical presentations and lack of widely accepted diagnostic criteria. We report a 46-year-old man who presented with an acute depressive episode and was proven to have encephalopathy associated with Hashimoto's thyroiditis. The exclusive psychiatric manifestations of this case called our attention to the fact that an improved awareness of EAATD in patients with a history of thyroid disease can lead to a timely diagnosis and excellent disease prognosis. © 2011 Elsevier Inc. All rights reserved. Keywords: Autoimmune thyroiditis; Encephalopathy; Hashimoto's disease 1. Introduction Encephalopathy associated with autoimmune thyroid disease (EAATD) is a rare condition associated with Hashimoto's thyroiditis or Grave's disease [1–3]. It is characterized by protean but nonspecific symptoms such as focal neurologic deficit, myoclonus, seizure, consciousness disturbance, depression and psychosis [2]. Among previ- ously published studies, few reported cases had psychiatric symptoms only [3,4]. Herein, we present a case of EAATD with exclusive psychiatric symptoms. There were a very early diagnosis and a good treatment response and prognosis. 2. Case report Mr. H, a 46-year-old man with no prior neuropsychiatric history, presented to our psychiatric unit with severe anxiety and agitation that began 2 days earlier. The family reported that the patient was physically well except for the history of abnormal thyroid function found at a health check-up in his 30s. There was no known prior treatment for thyroid disease, substance abuse or recent infection. The family history was unremarkable. During hospitalization, the patient appeared slow in verbal response and withdrawn. He denied any delusion or hallucination. The clinical impression was depressive disorder. The neuropsychological testing revealed a 30/30 Mini-Mental State Exam score and mild impairment of his psychomotor speed. The neurologic examination was normal. We performed thorough laboratory studies for the reported thyroid disease history, and Hashimoto's thyroiditis (antithyroglobulin Ab 154.07 IU/ml, normal b14.4 IU/ml; anti-TPO Ab 1697.78 IU/ml, normal b5.61 IU/ml) with hypothyroidism (free T4 0.53 ng/dl, normal range 0.89∼1.79 ng/dl; TSH 66.7 μIU/ml, normal range 0.25∼4.0 μIU/ml) was found. The thyroid ultrasonography showed a heterogenous isoechoic picture. Other serum autoimmune profiles (antinuclear antibody titer, anti-double- stranded DNA, antiphospholipid antibody, lupus anticoagu- lant) were within normal ranges, except the elevated serum IgG (2500.00 mg/dl, normal range 700∼1600 mg/dl). The patient received L-thyroxine 150 μg/day beginning on the third day of hospitalization. On day 7 of hospitalization, the patient suddenly cried in front of the nursing station, maintaining that he was going to be killed. On day 8, he denied what he had Available online at www.sciencedirect.com General Hospital Psychiatry 33 (2011) 641.e7 – 641.e9 ☆ The authors report no competing interests. ⁎ Corresponding author. Tel.: +886 2 23123456x66788; fax: +886 2 23819873. E-mail address: mctseng@ntu.edu.tw (M.-C.M. Tseng). 0163-8343/$ – see front matter © 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.genhosppsych.2011.05.019