Measurement uncertainty for practical use – applied in hematology

Uncertainty of measurements in clinical laboratories should be monitored, reported, and documented as required by accreditation standards. The conceived complexity of calculation methods described by current guidelines such as ISO 20914 favors a more pragmatic, utilitarian approach. For that reason an alternative approach was applied for measurement uncertainty (MU) calculations in a conglomerate of seven laboratories with eleven measurement systems. MU was based on internal quality control results and for the routine hematological parameters. Graphical and variance component analysis was used to identify factors causing diverging results. MU for hematological tests, but not for all derived parameters were within the MU-APS limits (MAU) based on biological variation. It was demonstrated that MU of a diverging measuring system in the conglomerate could be improved by a correction procedure. In conclusion, that MU could be derived for hematological tests in a conglomerate of laboratories. All the parameters of cellular counting (except indices) were within the specifications based on biological variation. Factors causing deviating results within the conglomerate could be identified and significantl improved.