Dehydroascorbic acid and oxidative stress in haemodialysis patients

Background. The amount of dehydroascorbic acid contained within total ascor bic acid (oxidized as well as non-oxidized forms) in plasma, hereafter refe rred to as the dehydroascorbic acid fraction, may be a measure of oxidative stress during haemodialysis. In the present study, we determined this frac tion in chronic haemodialysis patients. Methods. Using high performance liquid chromatography, dehydroascorbic acid and total ascorbic acid levels were measured in 80 maintenance haemodialys is patients for a period of >2 years as well as in 49 controls, to examine a possible association of these compounds with clinical parameters and/or d rugs taken by the patients. Results. Dialysis patients who had an increased plasma urate level (P < 0.0 5) and had been taking allopurinol (P<0.05) or NSAID (non-steroid anti-infl ammatory drugs) (P<0.01), and dialysis patients who were younger (<less tha n or equal to>55 years), as compared with older dialysis patients (P<0.01), were found to have a lower dehydroascorbic acid fraction by multivariate a nalysis. Mean plasma dehydroascorbic acid levels and dehydroascorbic acid f ractions were significantly lower in the younger haemodialysis patients (4. 8+/-0.7 <mu>mol/l and 28.4+/-3.9%) than in healthy younger controls (13.3+/ -1.11 mu mol/l and 41.1 +/- 1.8%) (P<0.0001 and P<0.01, respectively). More over, a correlation was found between plasma dehydroascorbic acid fraction and plasma lipid peroxide (r=0.66, P<0.01) in patients who had not been tak ing allopurinol and/or NSAID. Conclusion. We found that dehydroascorbic acid fraction was related to pati ents' age, plasma urate level and to taking allopurinol or NSAID. Dehydroas corbic acid fraction may be another indirect index of oxidative stress.