The assays for iPTH were not standardized though approximately 80% of medical facilities in Japan used ELECSYS assay for intact PTH measurements (Roche Diagnostics, Mannheim, Germany) (personal communication with Dr. Hitoshi Kato, who was involved in developing clinical guideline for the management of mineral and bone disease in chronic kidney disease for Japanese Society for Dialysis Therapy). This evidence concerns the gene PTH and chronic kidney disease.