1. The Fourth Department of Internal Medicine, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan
2. Third Department of Internal Medicine and
3. Department of Clinical Laboratories, Asahikawa Medical College, Asahikawa 078-8510, Japan
4. First Department of Internal Medicine, Saitama Medical School, Saitama 350-0495, Japan
5. Fourth Department of Internal Medicine, Tokai University, School of Medicine, Kanagawa 259-1193, Japan
6. Eiken Chemical Co., Ltd., Tokyo, 114-0002 Japan
7. Kuopio University Hospital, Kuopio 70211, Finland