Calculation of measurement uncertainty of 20 Clinical Chemistry Analytes according to the practical ISO approach

Purpose: Measurement Uncertainty (MU) is a valuable tool for evaluating analytical performance and interpreting results in clinical laboratories. The International Organization for Standardization (ISO) has proposed a practical approach for MU calculation in its ISO/TS 20914:2019 guide. This study aimed to calculate the MU values of 20 clinical chemistry analyses per the ISO guideline and compare them with the Maximum expanded allowable measurement uncertainty (MAU) values. 
Methods: The study was performed using 6-month internal quality control (IQC) values (uRw) and calibrator uncertainty (ucal) in line with the recommendations of the ISO/TS 20914:2019 guideline. The common MU value was calculated for 20 clinical chemistry tests on two identical devices, Roche Cobas 6000 c501 (Roche Diagnostics, Mannheim, Germany) analyzers. The calculated MU values for the tests were compared with the current MAU values in the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) Biological Variation database (the current Clinical Laboratory Improvement Amendments/CLIA recommendation for Ethanol has been selected). 
Results: MU values for Alanine aminotransferase, C-reactive Protein, Iron, Ethanol, Total Bilirubin, Triglyceride, and Blood urea nitrogen remained within the MAU limits. The MU values of the other 13 tests (excluding Aspartate aminotransferase, Glucose, and Potassium Level 2 IQC) exceeded the MAU values. 
Conclusion: It was observed that the uRw value affected the MU value the most. Close monitoring and evaluation of uRw and thus IQC and implementation of corrective and preventive actions may reduce MU.