Abstract: 　Objective　To explore the clinical characteristics of hyperthyroidism crisis in children. Method　The clinical data of hyperthyroid crisis complicated with multiple organ failure in a child was analyzed retrospectively. Results A 13-year-old girl had no history of thyroid disease. The initial symptoms included nausea, vomiting and lethargy, and the main manifestations at admission included arrhythmia, cardiogenic shock, and heart failure, so it was considered as fulminant myocarditis. Physical examination at admission revealed mild exophthalmos, and thyroid function test revealed significantly increased free T3 (FT3) and free T4 (FT4) and significantly decreased thyroid stimulating hormone (TSH). After admission, the patient successively developed respiratory failure, renal failure, and hepatic failure. The thyroid storm score was 120 points and accordingly the diagnosis of thyroid storm was confirmed. After treated with active antiarrhythmic treatment, vasoactive agents, respiratory support, propylthiouracil, iodine, glucocorticoids, and blood purification, etc., the patient was eventually discharged with improved condition. Conclusions　Thyroid storm is a rare condition in children. It can have thyroid diseases as its initial presentation in children. Early identification and management are the keys to successful treatment.

Key words: 　thyroid storm;　multiple organ failure;　fulminant myocarditis