Mass spectrometry based precision diagnostics: on the cusp of selective testing

New technologies and advances in human biology are paving the way for better patient management and outcomes in laboratory medicine. Precision diagnostics, as an essential component of P5 medicine, implies a shift towards selective testing of defined measurands, enabling a higher understanding of interindividual diversity and (patho-)biology at the molecular level. Precision diagnostics can potentially overcome some of the current inadequacies in diagnostic care pathways, caused by suboptimal tests leading to misclassifications and avoidable patient harm. Additionally, molecular methods have the potential to be standardizable upfront, allowing embedding of the metrological traceability concept. Over the last decade, especially mass spectrometry (MS) is gaining momentum and proving its potential as a selective measurement method for immunoassay replacement, add-on test and/or reference measurement procedure (RMP). In this context, the current place of MS in laboratory medicine is discussed, followed by cases from laboratory developed tests (LDTs), commercially available tests, highlighting also future MS applications. It is time for a wake-up call to promote a selective testing approach that accurately resembles individual biology, principally to be used when molecular definition is clinically relevant for classification ability and patient benefit. We provide a compilation for the laboratory specialist when to opt for molecularly defined tests. Ideally, the evolution to precision diagnostics is part of a changing healthcare landscape, where molecular fingerprints and patient diversity are inclusive. This will enable early detection of preclinical symptoms and start a shift from curative to preventive and personalized care.