Urine has always been one of the most suitable body fluids for clinical applications. Absolute quantification of disease protein biomarkers in body fluids such as urine is a key step in the biomarker development pipeline. Nevertheless, identification of groups of proteins in complex biological samples is challenging. Traditional affinity-based methodologies such as ELISA are used to verify the presence of biomarkers in clinical samples. More recently, targeted mass spectrometry-based strategies have been developed for biomarker validation, offering an alternative. The great advantage of targeted mass spectrometry-based methodologies is that they allow accurate and specific simultaneous quantification of several biomarkers (multiplexing). Peptides are used as protein surrogates, measured using triple quadrupole instruments in selected reaction monitoring/multiple reaction monitoring mode. In this review, the workflow of selected reaction monitoring/multiple reaction monitoring for disease biomarker validation in urine is presented and assay performance in the latest studies is described.
Keywords: absolute quantification; biomarker validation; multiple reaction monitoring; selected reaction monitoring; targeted proteomics; urine.