NIST's role in measurement accuracy for diagnosis and monitoring of diabetes.

Abstract

77 THE NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY (NIST), formerly the National Bureau of Standards, is an agency of the U.S. Department of Commerce. The mission of NIST is “to develop and promote measurement, standards, and technology to enhance productivity, facilitate trade, and improve the quality of life.” As health care and the industry that supports it cut across all of these areas, NIST has a long history of supporting accuracy in health care measurements. The objectives of this effort are to develop and maintain the measurements and standards infrastructure to facilitate accurate decision making in the diagnosis, treatment, and prevention of disease. NIST efforts in support of health care measurements have focused on development of accurate methods, definitive and reference methods as defined by NCCLS1 and on development of Standard Reference Materials (SRMs). SRMs are well-characterized materials with certain properties quantified with stated uncertainties. SRMs may be in the form of pure crystalline materials with certified purity, they may be aqueous or organic solutions with certified concentrations of one or more analytes, or they may be natural matrix materials, such as human serum, with certified concentrations of analytes. Certified values are obtained by a variety of modes,2 but in almost all cases, the certification measurements include measurements made at NIST using methods developed and critically evaluated at NIST. To learn more about NIST SRMs, see http://srmcatalog. nist.gov/. Initial efforts to develop SRMs to address clinical measurement needs began in the 1960s and were aimed at correction of errors associated with calibration. At that time, most methods involved preparation of calibrants from crystalline materials. The purity of such materials varied greatly, so NIST undertook development of a number of crystalline SRMs for commonly measured serum analytes. One of these was glucose for which NIST developed SRM 917, certified in 1970 to be 99.96 0.1 mass percent pure. The current lot of this material, designated as SRM 917b, is certified to be 99.7 6 0.2 mass percent pure. The newer material is not necessarily less pure; more sensitive analytical techniques are available now for detecting impurities that might have been missed in characterizing earlier materials. SRM 917b also has reference values for the optical rotation to serve as a standard for polarimetry. The next challenge was to develop higher order methods, called definitive methods, for measuring these analytes in serum. This method development work began at NIST in the 1970s for both organic and inorganic constituents. For both organic and inorganic species, the primary approach used was based upon isotope dilution mass spectrometry. Most elements come in several isotopic forms. The