Myeloperoxidase concentrations in EDTA-plasma of healthy subjects are discordant with concentrations in heparin-plasma and serum

To examine the effect of blood anticoagulation type on the myeloperoxidase (MPO) concentration. MPO was measured in EDTA-plasma and matched heparin-plasma and serum samples collected from healthy volunteers. MPO concentrations in heparin-plasma and serum were higher than in EDTA-plasma (both P < 0.001). MPO in EDTA-plasma was not significantly correlated with MPO in either heparin-plasma or serum. For MPO measurements, EDTA-plasma is the preferred specimen as it appears unaffected by ex vivo release of MPO from leukocytes.