1. Department of Occupational Diseases, Shenzhen Prevention and Treatment Control Center for Occupational Diseases, Shenzhen, Guangdong 518001, P.R. China
2. Department of Ultrasound, Shenzhen Prevention and Treatment Control Center for Occupational Diseases, Shenzhen, Guangdong 518001, P.R. China
3. Department of Endocrinology and Metabolism, The Second People's Hospital of Nantong, Nantong, Jiangsu 226000, P.R. China