Serum protein standardization project in Japan: evaluation of an IFCC reference material (RPPHS/CRM470) and establishment of reference intervals.

Reference preparation for proteins in human serum (RPPHS), also called Certified Reference Material 470 (CRM 470), was prepared by the international Federation of Clinical Chemistry (IFCC) and is intended to serve as a new international plasma protein reference material. It is now being introduced into Japan. RPPHS possesses many excellent properties, including safety, stability, and accuracy in value assignment. Moreover, the physicochemical properties of its proteins are identical to those of fresh serum, giving it immunochemical behavior that is commutable with that of existing reference materials and calibrators in given immunoassays. Reference intervals of 13 serum proteins were determined for the first time using nephelometry and a new working calibrator assigned from RPPHS, which seems certain to play a critical role in the global standardization of specific protein immunoassays.