Caveats of Untargeted Metabolomics for Biomarker Discovery

High-abundant metabolites can suppress the ionization of low-abundant metabolites by picking up most of the available charges at the cone of the spray tip (6). [...]the signal intensity is not solely dependent on the plasma concentration of the metabolite. [...]many issues remain to be addressed before claims can be made regarding the clinical utility of the presented findings (1), in particular the pre-analytical variation and confounding by medication, the reproducibility of the measurements, and most importantly, whether the additional information ultimately helps the clinician to manage patients and guide treatment decision by outperforming existing biomarkers (10).