Objective: Measurement uncertainty is a useful method to obtain objective information about laboratory performance, to identify analytes that need analytical improvement in clinical use, and to abandon analytes of inadequate quality. The aim of the study was to calculate the measurement uncertainty of the NT-proBNP test, for which no measurement uncertainty study has been conducted before, according to the Nordtest guideline, and to compare these calculated values with the total allowable error levels of Clinical Laboratory Improvement Amendments 2024.

Materials and Methods: The measurement uncertainty calculation model defined in the Nordtest guideline was used to calculate the measurement uncertainty of the NT-proBNP test and the uncertainty sources were determined. The data were analyzed retrospectively. The Clinical Laboratory Improvement Amendments 2024 total allowable error level of %TEa ± 30 for NT-proBNP was compared with the value obtained from our study.

Findings: In the study, the expanded uncertainty value (U) for the NT-proBNP test was calculated as approximately 6. In the process of calculating the within-laboratory reproducibility (uRw), it was concluded that the internal quality control coefficients of variation (% CV) affect the measurement uncertainty and that it is important to keep these values as low as possible.

Conclusion: The calculated measurement uncertainty value was found to be approximately 6, and it was seen that this value did not exceed the given limits when compared with the total allowable error level of Clinical Laboratory Improvement Amendments 2024. Laboratories should perform measurement uncertainty calculations of the tests and relevant clinicians should be informed about the obtained data.