The ferroxidase activity of caeruloplasmin is reduced in haemodialysis patients

increased free-radical production leading to oxidative stress may contribut e to the development of cardiovascular complications in haemodialysis patie nts. The ferroxidase activity of caeruloplasmin forms an important componen t of antioxidant defences in body fluids. The aim of this study was to asse ss ferroxidase activity in haemodialysis patients. Venous blood was collect ed from 83 haemodialysis patients im mediately prior to a nd after dialysis and from 52 healthy controls. Immunoreactive caeruloplasmin was measured b y rate nephelometry, and ferroxidase activity determined by measuring loadi ng of ferrous iron onto iron-free transferrin. A significant reduction in f erroxidase activity was observed in dialysis patients when compared with co ntrols (37 +/- 1.20 and 46 +/- 1.14 mU/l, respectively; p < 0.001). Followi ng dialysis, ferroxidase activity rose significantly to 41 +/- 1.16 mU/l, w ith a significant difference still remaining between control and patient fe rroxidase activity (p < 0.005). Immunoreactive caeruloplasmin was found to be similar in all groups (before dialysis 0.40 +/- 0.07 g/l, after dialysis 0.39 +/- 0.07 g/l, control 0.42 +/- 0.09 g/l: p = NS). A significant diffe rence in caeruloplasmin-specific activity was therefore observed between pr edialysis, postdialysis and control samples (97 +/- 2.31, 105 +/- 1.74 and 112 +/- 1.51 mU/g; p < 0.001, p < 0.07, respectively). Ferroxidase activity of caeruloplasmin is impaired in renal failure. Inhibition of caeruloplasm in ferroxidase activity in dialysis patients may contribute to increased ox idative stress in these patients. Copyright (C) 2000 S. Karger AG. Basel.