CAERULOPLASMIN FERROXIDASE ACTIVITY INPATIENTS TREATED BY CHRONIC HAEMODIALYSIS
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Increased free-radical production leading to oxidative stressmay contribute to the development of cardiovascular complications in haemodialysis patients. The ferroxidase activity ofcaeruloplasmin forms an important component ofantioxidant defences in both fluids. The aim of this studywas to assess ferroxidase activity in haemodialysis patients. Venous bloodwas collected from52 haemodialysis patients immediately prior to and after dialysis and from20 healthy controls. Immunoreactive caeruloplasmin was measured by rate phelometry, and ferroxidase activity determined by measuring loading offerrouriron into iron-free transferrin. Asignificant reduction in ferroxidase activitywas observed in dialysis patients when compared with control (36.9 + 0.98 and 45.5 + 1.11 mU/L, respectively; PO.001). Following dialysis, ferroxidase activity rose significantly to 41.3 + 0.56 mU/L, with a significant difference still remaining between control and patient perroxidase activity (PO.005). Immunoreactive caeruloplasminwas found to be similar in all groups. A significant difference in caeruloplasmin-specific activitywas therefore observed between predialysis, postdialysis and control samples (93.8 + 11.8 mU/g, 105.+ 23.3 mU/g, 110.9 4^12.7mU/g). Ferroxidase activity of caeruloplasmin is impaired in renal failure may be due to dialysable substances and also by post-translational modification of caeruloplasmin. This decrease in caeroplasmin ferroxidase activity in dialysis patients may contribute to increased oxidative stress in these patients.