Endocrine Abstracts

Goitre and hypothyroidism are well-established complications of lithium therapy; however, lithium-induced hyperthyroidism (LIH) is rare, with an incidence of 1.0–1.7%. First reported in 1976, the mechanism underlying this paradoxical phenomenon remains poorly understood. Hypotheses suggest autoimmune overactivity or direct lithium-induced thyroid destruction. We present the case of a 32-year-old gentleman with schizoaffective disorder and ADHD, on lithium carbonate and clozapine, who presented with a 2-week history of vomiting, agitation, and confusion. He denied thyroid hormone use or any personal or family history of thyroid disease. On presentation, his vital signs were HR 131 bpm, temperature 38.4°C, BP 138/72, RR 21, and oxygen saturation 95% on room air. Clinical examination revealed hypovolemia, though his thyroid exam was unremarkable. Initial management targeted acute kidney injury and dehydration. Lithium toxicity was ruled out with levels at 0.5 mmol/L (0.4–1). Persistent fever, psychotic deterioration, and confusion led to thyroid testing, showing T4 >100 pmol/L (11–22) and TSH 0.02 mU/L (0.27–4.2). Negative thyroid antibodies and reduced uptake on radioactive thyroid imaging suggested destructive thyroiditis. A Burch-Wartofsky score of 65 confirmed thyroid storm secondary to thyroiditis. The patient was treated with carbimazole 40mg daily, prednisolone 30mg daily, propranolol 40mg twice daily, and clonazepam 2mg three times daily, replacing lithium. His symptoms improved after 6 days of treatment. In summary, lithium-induced hyperthyroidism (LIH) poses challenges due to its unpredictable onset, lack of management consensus, and potential need to discontinue lithium. Diagnosis is complicated as LIH symptoms often overlap with mania, and lithium levels are frequently within normal range. Treatment is further complicated by interactions between antithyroid and psychiatric medications, which can lead to the re-emergence of psychotic symptoms. These challenges highlight the urgent need for further research into risk factors and the development of tailored monitoring and treatment approaches.