Subacute thyroiditis presenting as acute psychosis: a case report and literature review
An 18-year-old male presented to the emergency department due to abnormal behavior, agitation, and increased activity. One week prior to this visit, the patient had reported experiencing dizziness, headache, and sore throat, for which he had taken a cold medicine which had included a nonsteroidal anti-inflammatory drug. Three days prior to the emergency department visit, the patient had reported experiencing anxiety, irritability, and restlessness, which subsequently worsened to additional features of psychomotor agitation and a paranoid mental state. The patient was healthy with the exception of these psychomotor problems; he reported doing well in school and maintained good interpersonal relationships. There was no history of recent or past alcohol or drug abuse and there was no family history of psychiatric disorders.\nOn arrival, the patient appeared agitated and had a poor attention span. He complained of a sore throat, febrile sensation, and dizziness. He was irritable and threatening, as well as talkative. His speech was irrational and seemingly random. The patient also exhibited persecutory delusions toward his mother. Physical examination revealed tachycardia with a heart rate over 100 beats/min, moist skin, and an elevated body temperature (37.8℃). Chest and abdominal examinations revealed no abnormalities.\nLaboratory findings included a leukocyte count of 6.02 × 109/L, an erythrocyte sedimentation rate (ESR) of 36 mm/hr (normal range, 0 to 9), aspartate aminotransferase of 38 IU/L, alanine aminotransferase of 62 IU/L, and high sensitive C-reactive protein of 0.21 mg/L (normal range, 0 to 5). Brain computed tomography and subsequent lumbar puncture revealed no abnormal findings. Thyroid function tests revealed a thyrotoxic state with free T4 of 100.0 pmol/L (normal range, 11.5 to 22.7) and thyroid stimulating hormone (TSH) of 0.018 mU/L (normal range, 0.27 to 4.2), antithyroid peroxidase antibody and anti-TSH receptor antibody testing were negative. The patient's thyroid gland was hard and mildly enlarged, and he reported tenderness on palpation. Subacute thyroiditis was suspected, but the patient's uncooperative state prohibited further diagnostics. We subsequently consulted the psychiatry department. According to the clinical symptoms and laboratory results, a psychiatrist diagnosed the patient with a mood disorder due to a general medical condition (Diagnostic and Statistical Manual of Mental Disorders 4th edition, 293.83), and the accompanying symptoms were presumed to be the result of a thyrotoxic state caused by subacute thyroiditis.\nThe patient was admitted to a closed ward in the psychiatric department for careful observation. Symptomatic treatment and heart rate control with a beta blocker (propranolol 20 mg twice daily), was continued, and antipsychotic drugs, including haloperidol 5 mg daily and lorazepam 4 mg daily, were also used. Over the first 3 days of admission, the patient's increased activity, especially sexual hyperactivity, and offensive attitude did not subside, but after 2 weeks, marked improvement was observed in all symptoms. Subsequent blood tests revealed improved thyroid function with a free T4 of 41.4 pmol/L, and TSH of 0.01 mU/L. The patient's overall condition was markedly better and he was more cooperative. Therefore, thyroid ultrasonography and a technetium-99m (99mTc) scan were performed. The sonographic findings included multifocal heterogeneous echogenicity with normal gland size and decreased vascularity (). The 99mTc pertechnetate scan revealed homogenously reduced Tc uptake in the thyroid gland (20 minutes Tc-pertechnetate uptake, 1.1%) ().\nApproximately 20 days after hospitalization, the patient's free T4 level had decreased to nearly normal and he was gradually weaned off the antipsychotics before being subsequently discharged. On follow-up, the patient remained asymptomatic and has since returned to school without recurrence of psychiatric symptoms ().