1. Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.
2. Institute of Endocrine Research, Yonsei University College of Medicine, Seoul, Korea.
3. Division of Endocrinology and Metabolism, Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea.
4. Department of Internal Medicine, Wonkwang University Hospital, Wonkwang University School of Medicine, Iksan, Korea.