1. Division of Endocrinology, Department of Medicine, Myongji Hospital, Seonam University College of Medicine, Goyang, Korea.
2. Department of Social and Preventive Medicine, Sungkyunkwan University School of Medicine, Seoul, Korea.
3. Division of Endocrinology and Metabolism, Department of Medicine, Thyroid Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.