Albumin as a Biomarker

Abstract

Recent advancements in technology have given rise to the emergence of data regarding posttranslational modifications of human serum albumin (HSA) such as oxidation, glycation, truncation, dimerization, and carbamylation in disease conditions. We developed a simple and rapid analytical method that allows the redox state of Cys-34 of HSA to be quantitatively and qualitatively evaluated with a high degree of sensitivity using an ESI-TOFMS technique. An increase in the level of oxidized HSA accompanied by a decrease in the level of reduced HSA was observed in cases of chronic liver disease, chronic renal disease, and diabetes mellitus, although the redox state of HSA is not associated with colloid osmotic pressure. The degree of oxidation of Cys-34 was correlated with ligand binding and the anti-oxidative functions of HSA. Since there is no oxidized form of HSA immediately after its secretion from liver cells, the oxidized species could constitute a potential marker of the extent of oxidative stress and of the scavenging activity of Cys-34. Evidence has accumulated to demonstrate that monitoring of the redox state of Cys-34 could not only be a useful marker for evaluating the progression of oxidative stress-related disease and the development of its complications but also in predicting therapeutic efficacy. In addition, the usefulness of determining the redox state of Cys-34 as an index of the quality of HSA preparations was also shown. These data strongly suggest that monitoring the posttranslational modifications of HSA can be important, since HSA function is related not only to its serum concentration but also to the preservation of its structural integrity under disease conditions.