A Case of Hashimoto's Encephalopathy Manifesting as Psychosis

Abstract

Sir: A high rate of autoimmune thyroiditis not associated with lithium treatment has been reported in patients with psychiatric disorders.1,2 Hashimoto's encephalopathy is a rare subacute condition associated with high levels of thyroid antibodies that usually presents with neurologic symptoms. A few cases of this illness manifesting with predominant psychiatric symptoms have been reported.3–5 Case report. Mr. A, a 31-year-old man with no significant medical history, initially presented for treatment in January 2006 and had suffered from delusions, disorganized speech, talkativeness, racing thoughts, acute episodes of memory loss, reduced need for sleep, and irritability for 4 months. No alterations were found with physical examination or magnetic resonance imaging. Electroencephalography showed intermittent slow-wave activity. The results of general blood chemistries and a comprehensive drug screen were within normal limits. Thyroid function test revealed a free triiodothyronine (T3) level of 0.33 ng/dL, a free thyroxine (T4) level of 1.0 ng/dL, a total T4 level of 6.2 µg/dL, and a thyroid-stimulating hormone level of 5.60 µIU/mL. The patient was unsuccessfully treated with numerous psychotropic medications during this 4-month period. A new exhaustive physical examination showed myoclonic jerks and thyromegaly. Mr. A's thyroid peroxidase antibody titer was measured, and the result was positive at 7500 U/L. A diagnosis of Hashimoto's encephalopathy was considered, and steroid therapy was started, with significant improvement in the patient's mental status within 1 week. The steroid therapy was gradually tapered over 2 months, and the patient remained symptom-free and had thyroid peroxidase antibody titers within normal limits after 3 months. Hashimoto's encephalopathy diagnosis should be considered in patients with potential autoimmune thyroiditis and neuropsy-chiatric manifestations not responding to conventional therapy.