A case report of acute depressive symptoms associated with hyperthyroidism

Background Thyroid dysfunction is a well-established cause of secondary psychiatric disturbances. While hypothyroidism is classically associated with depressive symptoms and hyperthyroidism with anxiety and irritability, atypical presentations can occur. Here we report a case of hyperthyroidism that presented with prominent acute depressive symptoms—a manifestation that remains strikingly underrecognized and poses significant diagnostic challenges in psychiatric emergency settings. Case presentation A 31-year-old woman presented with a three-day history of mutism, intense guilt, frequent crying, insomnia, and loss of appetite. Examination revealed fever (37.5°C), tachycardia (121 bpm), and a tearful, largely mute affect. Emergency investigations including cranial CT and routine blood tests were unremarkable, and a preliminary diagnosis of acute psychotic disorder was made. Admission laboratory screening unexpectedly revealed marked hyperthyroidism: total thyroxine 319.14 nmol/L (reference: 69.71–163.95) and thyroid-stimulating hormone < 0.01 mIU/L (reference: 0.38–5.33). Thyroid ultrasonography and elevated thyroid-stimulating immunoglobulin confirmed Graves' disease with impending thyroid storm. The patient was treated with propranolol, propylthiouracil, and intensive care monitoring. Residual depressive symptoms responded to low-dose lithium carbonate (0.3 g daily) and risperidone (2 mg daily), with antidepressants deliberately avoided. Full remission was achieved by day 16. Retrospective history later revealed a one-year history of unreported hyperthyroid symptoms. Conclusion This case challenges the conventional dichotomy of thyroid-related psychiatric presentations, demonstrating that hyperthyroidism can present with predominantly depressive symptoms. Unreliable history and absent classic physical signs delayed diagnosis, underscoring the importance of routine laboratory screening in psychiatric emergencies. The combination of lithium and risperidone, with avoidance of antidepressants, offers a practical management strategy.