Elevated Fluorine-18-FDG Uptake in Skeletal Muscles: A Clue for the Diagnosis of Graves’ Disease

Received 10/7/2002; revised 10/30/2002; accepted 11/5/2002. For correspondence or reprints contact: Yen-Ling Chen, M.D., Department of Endocrinology and Metabolism, Shin Kong Wu Ho-Su Memorial Hospital. 95 Wen Chang Road, Shih Lin District, Taipei 111, Taiwan. Tel: (886)2-28332211 ext. 2032, Fax: (886)2-27044103, E-mail: [email protected] A 45-year-old woman complained of weakness, dizziness, tremor and loss of body weight 2 kg within one month. She was underwent a whole-body fluorine-18-2fluorodeoxyglucose (FDG) positron emission tomography (PET) study for physical check up. There was symmetric diffused high FDG uptake in the skeletal muscles. Results of thyroid function test were as follow: TSH was not measurable, whereas both T4 21 μg/dL and T3 381 ng/dL were increased. The image of thyroid echo was hypoechoic and heterogenous compatible with Graves’ disease. So that, the increment of muscle FDG uptake may be responsible for the high peripheral glucose utilization seen in Graves’ disease.