engleski

MEASUREMENT UNCERTAINTY FOR ROUTINE MEASUREMENT PROCEDURES IN CLINICAL CHEMISTRY LABORATORY ACCREDITED ACCORDING TO ISO 15189

Background. Medical laboratories accredited according to ISO 15189 have to meet standards of traceability and measurement uncertainty (MU). Since MU encompasses all random and non-corrected systematic errors, we evaluated whether the obtained MU for routine diagnostics tests meet “fitness for clinical purpose” by comparison with desirable analytical quality goals based on Stockholm Statements. Methods. The uncertainty components we use are uncertainties related to 1- calibrator, 2-within- laboratory precision and 3- trueness estimates based on the results of external quality assessment (EQA). Measurement uncertainties of routine quantitative biochemical assays are estimated on the basis of “Guide to the Expression of Uncertainty in Measurement”. Results. Biochemical analysis of metabolites, enzymes, proteins and electrolytes are performed on Olympus AU 600 multiparametric chemistry analyzer (Beckman Coulter Inc., USA). Traceability of analytical measurement procedures is achieved through a manufacturer’s reference materials (calibrators) or reference Methods. Analyzer–based calibrations are routinely performed for compensation of systematic effects. Estimates of within-laboratory precision are provided by internal quality control data in two concentration levels while participation in EQA allowed us to monitor long-term analytical bias. Conclusions. The obtained measurement uncertainties show that Institute of Clinical Chemistry and Laboratory Medicine of Clinical Hospital Merkur accredited according to ISO 15189 produces test results that are within the desirable analytical goals defined by European recommendations. According to our experience the GUM uncertainty should be applied to measurements in laboratory medicine as one of the prerequisites to fulfil the long-term clinical goal which is to compare test results produced by any laboratory at any time.

traceability; measurement uncertainty; desirable analytical quality goals; external quality assessment

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