Effect of blood sample type on the measurement of advanced oxidation protein products as a biomarker of inflammation and oxidative stress in hemodialysis patients.

Advanced oxidation protein products (AOPP) is widely used as a uremic biomarker, especially for cardiovascular disease. However, it has not been determined whether it is better to measure AOPP in plasma or serum. In this cross-sectional study, which included 102 patients undergoing maintenance hemodialysis, fibrinogen-free serum and defibrinated plasma samples were prepared. AOPP levels from fibrinogen-free samples displayed a stronger correlation with myeloperoxidase activity and levels of C-reactive protein, interleukin-6 and tumor necrosis factor-alpha, as well as prevalent cardiovascular disease, than AOPP levels obtained from plasma samples. These results demonstrated that fibrinogen interferes with the measurement of AOPP.