Consideration of Radioactive Iodine Therapy in a Graves' Disease Patient with Secondary Psychosis: A Case Report

Abstract Psychosis is a rare but recognized neuropsychiatric complication of hyperthyroidism, most commonly associated with Graves' disease. Although anxiety and mood disturbances are more frequent, acute psychosis has been reported in approximately 1% of cases. We report the case of a 30-year-old man with a 1-year history of Graves' disease who developed acute psychotic symptoms, including hallucinations and disorganized behavior. Laboratory findings revealed severe thyrotoxicosis with a suppressed thyroid-stimulating hormone and markedly elevated free T4. Thyroid scintigraphy using technetium-99m pertechnetate demonstrated diffuse increased uptake consistent with toxic diffuse goiter. The patient with severe thyrotoxicosis was initially managed with methimazole, propranolol, and psychiatric medications. Although the scheduled 1-week follow-up was missed, he returned at 4 weeks while continuing his prescribed therapy. At that visit, repeat thyroid function tests were obtained and psychiatric care was maintained. Subsequently, radioactive iodine (RAI) therapy at a fixed dose of 370 MBq (10 mCi) was administered after a short withdrawal of antithyroid drugs. One month posttreatment, both thyroid function and psychiatric symptoms improved significantly, allowing for discontinuation of antipsychotics. At 3 months, he became hypothyroid and was started on levothyroxine replacement. This case highlights the importance of a multidisciplinary approach in managing patients with coexisting psychiatric conditions. Psychosis secondary to hyperthyroidism may mimic primary psychiatric disorders, potentially delaying diagnosis. Stabilizing psychiatric symptoms prior to definitive therapy and ensuring close psychiatric follow-up are essential to achieving optimal clinical outcomes. Radioiodine remains a safe and effective treatment for Graves' disease, even in patients with neuropsychiatric complications. The psychotic symptoms in this case are caused by hyperthyroidism. RAI therapy can effectively and safely treat hyperthyroidism in Graves' disease patients with secondary psychosis.