Ceruloplasmin:: measurement of serum ferroxidase activity

Ceruloplasmin (Cp) is the principal copper carrier in human plasma. It is an abundant protein that participates in the acute phase reaction to stress, but its physiological function is unknown. Althought Cp is synthesised predominantly in the liver, other cell types express the protein, including monocytes, astrocytes and Sertoli cells. The serum concentration of the copper protein ceruloplasmin has been an important diagnostic indicator of Wilson's disease. Measurement of the total amount of Cp protein may not reflect Cp enzyme activity in the serum. The immunologic assay may lead to overestimation of the total amount of functional Cp in the serum due to this method's capacity to determine both the functional holo Cp and non-functional apo Cp. Several methods for determining ferroxidase activity have been reported. In this study, a method is described for automated measurement of the activity. In this method, Fe2+ ions are used as the substrate. The range for serum Cp ferroxidase activity in healthy persons was 424-796 UI/L for women, and 397-733 UI/L for men. Significant correlations between serum ferroxidase activity and Cp concentration (r=0,7285; p < 0,0001) were found.