Standardization of protein biomarker measurements: is it feasible?

The standardisation of measurements of protein biomarkers, which are potentially heterogeneous in terms of fragmentation, modification, substitution, primary, secondary, tertiary and quaternary structure, is a demanding task. However, they are a prime target for standardisation efforts due to the importance of protein biomarkers in diagnostics and health care and the typically observed significant discrepancies in measurement results obtained with non-standardized platforms. Based on the experience gathered during successfully completed projects for the production of reference materials, pragmatic approaches are described how standardisation could become feasible despite the fuzziness of the target analytes.