Abstract: 　Objective　To analyze the clinical data of one adolescent girl who suffered from Hashimoto encephalopathy with the onset of status epilepticus and high fever. Methods　Clinical data of the patient was retrospectively analyzed and related literatures were reviewed. Results　An adolescent girl was diagnosed with Hashimoto encephalopathy with the onset of status epilepticus and high fever. Under the continuous intravenous injection of sodium valproate for 57 hours and corticosteroids and intravenous immunoglobulin treatment, convulsions was stopped. For twice lumbar punctures, the cerebrospinal fluid analysis showed no obvious abnormalities. Antibodies against autoimmune encephalitis in the blood and cerebrospinal fluid were all negative. No abnormality was found in the head CT and MRI. After 67 hours of admission to the hospital, the patient was conscious. She became afebrile after 72 hours. Electroencephalogram for 24 hours indicated diffuse slow wave and no typical epileptiform discharge. There was no abnormal analysis of blood amino acids, acyl carnitine and urinary organic acids. Blood lactate and blood ammonia were in normal range. The detection of thyroid function indicated that the titers of antithyroglobulin antibody and thyroid peroxidase antibody increased significantly, free T3 was lower than normal and sTSH was higher than normal. Therefore, the diagnosis was Hashimoto encephalopathy. Levothyroxine sodium tablets and prednisone were given to the patient. We monitored the thyroid function and adjusted the dosage of medicine. After discharge from the hospital for 3months, the thyroid function was normal and the electroencephalogram was normal under the treatment of oral levothyroxine sodium tablets 50μg/d and prednisone 5 mg/d. The patient was still in the follow-up. Conclusions　Hashimoto encephalopathy is a rare disease, easy to be misdiagnosed and missed. Therefore, for adolescents with status epilepticus and fever, the thyroid function and thyroid associated antibodies, especially thyroid peroxidase antibody, should be routinely screened for early diagnosis and early treatment to improve the prognosis. Further research is still needed because the pathogenesis of the disease is not yet clear.

Key words: Hashimoto encephalopathy;　status epilepticus;　high fever;　thyroid peroxidase antibody