[A woman in her twenties with paranoid delusions]

Background: A woman in her twenties was admitted to the psychiatric ward with suspected psychosis. Routine tests revealed a rare and potentially dangerous cause of her symptoms.
Case Presentation: The patient had a history of bipolar II disorder, recurrent depressive disorder and hypothyroidism, and presented to the psychiatric emergency department with a one-week history of delusions of persecutory character and increasing insomnia. She had given birth four months prior to admission. Clinical examination was otherwise unremarkable. Bipolar psychosis was considered the most likely diagnosis, and she was started on antipsychotic medication with quetiapine 100 mg × 2. Routine blood tests revealed severe hypothyroidism with thyroid stimulating hormone (TSH) of 151,00 mIU/L and free T4 (fT4) of <3,0 pmol/L (9,5-22,0), and the patient was treated with a high dose of oral levothyroxine. After a few days the patient's psychiatric symptoms resolved completely, and her fT4 increased to 10,8 pmol/L. Upon further questioning, the patient admitted to increasing fatigue and constantly feeling cold over the previous few months, which she attributed to being a parent. She was discharged after a week without any psychiatric symptoms.
Interpretation: This case report highlights the importance of a broad somatic differential diagnostic approach to patients with psychosis.