1. Division of Rheumatology, Endocrinology and Nephrology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
2. Division of Laboratory and Transfusion Medicine, Hokkaido University Hospital, Sapporo, Japan
3. Department of Biostatistics, Yokohama City University, Yokohama, Japan
4. Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama, Japan