1 doi: 10.2169/internalmedicine.2681-19 Intern Med Advance Publication http://internmed.jp 【 CASE REPORT 】 The Delayed Diagnosis of Thyroid Storm in Patients with Psychosis: A Report of Two Cases Yuki Ishihara 1 , Taku Sugawa 1 , Hiroki Kaneko 1 , Kaho Hiroshima-Hamanaka 1 , Aya Amano 1 , Hironobu Umakoshi 1 , Mika Tsuiki 1 , Toru Kusakabe 2 , Noriko Satoh-Asahara 2 , Akira Shimatsu 3 and Tetsuya Tagami 1,2 Abstract: We herein report two cases of patients with thyroid storm with a delayed diagnosis due to psychosis. The patients were a 63-year-old woman with bipolar II disorder and a 37-year-old man with major depressive dis- order. The psychoses in both patients were well controlled with medication. Although they both showed symptoms of thyrotoxicosis, the symptoms were ignored, presumably because the psychological manifesta- tions of worsening of psychosis and thyroid storm are similar. When the mental or physical state of patients with psychosis changes, thyroid hormone levels should be measured for early treatment. Key words: thyroid storm, Graves’ disease, central nervous system, psychosis (Intern Med Advance Publication) (DOI: 10.2169/internalmedicine.2681-19) Introduction Thyroid storm is a medical emergency that is associated with multiple-organ dysfunction due to a failure of normal homeostatic mechanisms to cope with excessive thyroid hor- mone levels. It may develop in patients with thyrotoxicosis who are under severe stress (1). In Japan, thyroid storm has been reported in approximately 0.2 per 100,000 persons per year with a mortality rate that exceeds 10% (2). Central nervous system (CNS) manifestations, including the pres- ence or absence of consciousness disorder, are important for the clinical diagnosis and outcomes of thyroid storm in Ja- pan (1, 3, 4). However, such manifestations can be diverse and easily misinterpreted as psychosis (2, 5), which is con- founded in cases where patients with psychosis. In this study, we report two cases of patients with thyroid storm that were diagnosed late. Case Reports Case 1 A 63-year-old Japanese woman with bipolar II disorder had been treated with medication at a psychiatric hospital. Her mental state had been stable for over three years. How- ever, in the past two months, the deterioration of her depres- sion had been noted, accompanied by a decreased food in- take and extensive fatigue. She was admitted to a psychiatric hospital with a two-day history of emaciation and difficulty with dietary intake, at which point she experienced disorien- tation and developed incomprehensible speech and somno- lence. Therefore, she was transferred to our hospital. Her medical history was significant only for sciatica, and her family history was unremarkable. She was treated with mirtazapine, flunitrazepam, lorazepam, haloperidol, biperi- den, famotidine, rivaroxaban, and verapamil. On an exami- nation, she had a height of 156 cm, a weight of 40.8 kg, a body temperature of 38.9℃, tachycardia with 177 beats per １ Department of Endocrinology and Metabolism, National Hospital Organization Kyoto Medical Center, Japan, ２ Department of Endocrinology, Metabolism, and Hypertension Research, Clinical Research Institute, National Hospital Organization Kyoto Medical Center, Japan and ３ Clinical Research Institute, National Hospital Organization Kyoto Medical Center, Japan Received: January 16, 2019; Accepted: February 14, 2019; Advance Publication by J-STAGE: April 17, 2019 Correspondence to Dr. Yuki Ishihara, peasant1582@yahoo.co.jp