Plasma glutathione peroxidase activity is reduced in haemodialysis patients

Cardiovascular disease is the major cause of morbidity and mortality in pat ients with end-stage renal failure. Increased free radical production and a ntioxidant depletion may contribute to the greatly increased risk of athero sclerosis in these patients. Glutathione peroxidase (GPX) is an important a ntioxidant, the plasma form of which is synthesized mainly in the kidney (e GPX). The aim of this study was to assess the activity of eGPX in patients with end-stage renal failure on haemodialysis. Venous blood was collected f rom 87 haemodialysis patients immediately prior to and after dialysis and f rom 70 healthy controls. Serum eGPX activity was measured using hydrogen pe roxide as substrate and immunoreactivity determined by ELISA. eGPX activity was significantly reduced in dialysis patients when compared to controls ( 106 +/- 2.7 and 281 +/- 3.6 U/l respectively, p < 0.001). Following haemodi alysis, eGPX activity rose significantly to 146 +/- 3.8 U/l, p < 0.001, alt hough remaining below control values (p < 0.005). Immunoreactive eGPX, howe ver, was similar in all groups (pre-dialysis 14.10 +/- 1.26 mu g/ml, post-d ialysis 14.58 +/- 1.35 mu g/ml, controls 15.20 +/- 1.62 mu g/ml, p = NS). A decrease was observed in the specific activity of eGPX in patients when co mpared to controls (8.81 +/- 1.14, 10.71 +/- 1.54 and 21.97 +/- 1.68 U/mg r espectively, p < 0.0001). eGPX activity is im pal red in patients undergoin g haemodialysis and so may contribute to atherogenesis in renal failure.