1. Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.
2. Division of Endocrinology and Metabolism, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
3. Division of Endocrinology and Metabolism, Department of Internal Medicine, Research Institute of Clinical Medicine, Chonbuk National University Hospital, Chonbuk National University Medical School, Jeonju, Korea.
4. Division of Endocrinology and Metabolism, Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea.
5. Division of Endocrinology and Metabolism, Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.