Soo-Mee Bang1, Sang-Hoon Na2, Ji Hyun Kim3, Seo Ree Kim4, Seong-Rim Kim5, Seongsoo Jang6. 1. Department of Internal Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea. 2. Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea. 3. Department of Neurology, Korea University Guro Hospital, Seoul, Korea. 4. Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea. 5. Department of Neurosurgery, Bucheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Bucheon, Korea. 6. Department of Laboratory Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.