Clinical and Laboratory Standards Institute EP32—Implementation of Metrological Traceability in Laboratory Medicine provides guidance on establishing, validating, and documenting metrological traceability for end-user calibrators and results for human samples measured using in vitro diagnostic medical devices (IVD MDs) in medical laboratories based on the metrological traceability requirements for IVD MDs in ISO 17511. Though CLSI EP32 is intended for use primarily by manufacturers of IVD MDs, the concepts and approaches recommended may be extended to apply to measurements performed in the medical laboratory either with commercially available or laboratory-developed tests.

CLSI EP32-Ed2 replaces the previous edition of the approved report, CLSI EP32-R, published in 2006. CLSI EP32 has been completely rewritten and focuses on reflecting the changes implemented in the current edition of ISO 17511,1 specifically: 
• Metrological traceability of measurement results for HS, not just values assigned to product calibrators 
• Details on which calibrators in a calibration hierarchy must be commutable and how to handle noncommutability in these materials 
• Discussion of validation of metrological traceability 
Furthermore, seven worked examples have been developed to illustrate key aspects and considerations for different calibration hierarchies. An introduction to the worked examples is found in Appendix A. The worked examples are included as Appendixes B through H: 
• Appendix B: Worked Example of Glucose in Plasma 
• Appendix C: Worked Example of pH in Whole Blood 
• Appendix D: Worked Example of Alanine Aminotransferase Catalytic Concentration in Serum 
• Appendix E: Worked Example of Free Thyroxine in Serum 
• Appendix F: Worked Example of Hemoglobin A1c in Whole Blood 
• Appendix G: Worked Example of Human Chorionic Gonadotropin and Immunoglobulin G in Serum 
• Appendix H: Worked Example of D-dimer in Serum

CLSI EP32 provides information for implementing metrological traceability according to ISO 17511. It describes the necessary components and their use for in vitro diagnostic medical device (IVD MD) manufacturers to correctly establish, implement, and maintain metrological traceability. CLSI EP32 explains different calibration hierarchies for end-user medical laboratory measuring systems that are metrologically traceable to the highest available measurement procedures (MPs) and calibration materials. 

CLSI EP32 describes related procedures (eg, commutability assessment, estimation of measurement uncertainty [MU], and analytical performance specifications [APS]) used in implementing metrological traceability. However, CLSI EP32 refers to other publications for detailed design and execution of these procedures.