Riferibilità metrologica come strumento per la standardizzazione delle misure in Medicina di Laboratorio
Centro per la Riferibilità Metrologica in Medicina di Laboratorio (CIRME), Università degli Studi, Milano
Metrological traceability as a tool to standardize measurements in Laboratory Medicine
Basics for the correct application of the concept of metrological traceability in laboratory measurements are the univocal definition of the measurand and of an unbroken metrological traceability chain, the demonstration of the commutability of calibration materials, the correction of the measurement bias and the estimate of combined uncertainty at each level of the metrological chain. In vitro diagnostics (IVD) manufacturers should ensure traceability of their analytical systems to recognized higher-order references (materials and/or methods) and estimate the combined uncertainty of calibrators. End-users should check the IVD traceability through the verification that control materials of analytical systems are in the manufacturer’s declared validation range and through the organization of EQAS that meet metrological criteria. Separately, they should also estimate the contribution to measurement uncertainty by random effects. Main unsolved issues are the lack of full information about sources of traceability and uncertainty of commercial calibrators, the lack of objective analytical specifications and the need to properly define and use ‘traceable’ reference intervals.