Protein immunoassays provide information about quantities and forms of endogenous proteins. Uniplex enzyme immunoassays like Elisa have been the workhorse for protein measurement for decades, but they can be laborious and expensive and consume relatively large amounts of specimen. In comparison to the ELISA for a single analyte, multiplex assays offer the possibility of obtaining more reliable quantitative information in a highly parallel analysis. In addition, quantitative multiplexed assays offer the possibility to identify combinations of biomarkers with higher disease specificity than any single established biomarker alone. Because of these reasons, currently one-analysis, many-metabolites, manydiseases approach is receiving more attention than uniplex system with one-analysis, onemetabolite, one-disease.