Iatrogenic neuroleptic malignant syndrome revealing primary hyperthyroidism with thyrotoxic heart disease: A case report

Neuroleptic Malignant Syndrome (NMS) is a rare but life-threatening complication of antipsychotic medication, while hyperthyroidism is known to affect multiple organ systems, particularly the cardiovascular system. The concomitant occurrence of these conditions presents rare diagnostic and management challenges. We report a case of a 75-year-old female with hypertension who had been on neuroleptic therapy (Haloperidol, Promethazine) for depression for four months. She presented with altered general condition, hyperthermia (40.8 °C), altered consciousness, hypersialorrhea, aphasia, resting tremor, signs of thyrotoxicosis including exophthalmos and goiter, and global cardiac insufficiency. Laboratory investigations revealed severely suppressed TSH (0.001 mIU/L), markedly elevated FT4 (78 ng/L) and FT3 (20 ng/L), and bi-cytopenia. Imaging confirmed a hypervascularized diffuse goiter and echocardiography demonstrated hyperkinesia with elevated left ventricular ejection fraction (75 %). The patient was diagnosed with primary hyperthyroidism complicated by thyrotoxic heart disease, revealed by neuroleptic malignant syndrome. Management included immediate discontinuation of neuroleptics, initiation of antithyroid medication (Thiamazole), beta-blockade (Propranolol), and heart failure therapy. Complete resolution of symptoms was achieved within two weeks. This case highlights the importance of considering hyperthyroidism in the differential diagnosis of patients presenting with NMS, particularly when cardiovascular manifestations are prominent.