Diagnosing heart attacks may become an even more precise science with the advent of the first of a series of new clinical standards issued by the National Institute of Standards and Technology.

Standard Reference Material 2921--human cardiac troponin complex--is intended to help manufacturers develop and calibrate assays that measure specific protein concentrations in patient blood samples to determine whether a heart attack has occurred.

The SRM is a solution containing certified concentrations of three related proteins including cardiac troponin I, purified from human heart tissue from cadavers. Users can calibrate their assays by analyzing the SRM and comparing the results to the NIST-certified value for troponin I. The standard is expected to help reduce variations in clinical test results from as much as 50-fold on the same sample to twofold. "It’s a big first step toward getting the system under control," says Michael Welch, leader of the NIST development team.

Although NIST already produces more than 60 SRMs for the clinical diagnostics community, this is the first designed to help measure concentrations of large, protein-based health status markers. Troponin I is difficult to measure because it can exist in low concentrations and in different chemical forms, sometimes attached to other related proteins. NIST is developing additional standards and methods for measuring other health-status indicators of this type, including hormones used to assess thyroid function and other markers for heart attack risk.

SRM 2921 is intended to help U.S. makers of in vitro diagnostic medical devices sell their products in Europe. A European Union directive requires that such devices be calibrated with standards that are traceable to internationally recognized certified reference materials or procedures. SRM 2921 has been nominated for inclusion on the international list of higher-order reference materials. The list currently contains approximately 150 entries for 96 health status markers; NIST SRMs provide traceability for 72 of these.

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