Effect of high flux versus low flux hemodialysis on serum beta-2 microglobulin, advanced oxidation protein products and protein carbonyl

Background: The uremic syndrome is characterized by the retention of toxins that contribute to the associated morbidity and mortality. The heterogeneity of uremic toxins with respect to their molecular weight and protein binding may affect their removal by hemodialysis. Objectives: To investigate the effect of high flux versus low flux hemodialysis (HD) on serum beta- 2-microglobulin (B2MG) and advanced oxidation protein products (AOPP) as uremic toxins and protein carbonyl (PCO) as an oxidative stress marker in chronic HD patients. Methods: Twenty patients on chronic low flux HD were recruited from El-Shefaa Hospital in Alexandria. At the start of the study, all patients were switched to high flux HD for 8 weeks (period A), followed by 2 weeks low flux HD as a wash out period. Then, the patients had another 8 weeks of low flux HD (period B). Pre-dialysis serum samples were taken at beginning and end of period A (pre-high flux and post-high flux) and at beginning and end of period B (pre-low flux and post-low flux). B2MG was measured by ELISA, AOPP and PCO were assayed spectrophotometrically. Results: Post-high flux B2MG and PCO levels were significantly lower than pre-high flux levels (p=0.031 and 0.036, respectively), but no significant change was observed in AOPP (p= 0.8). Post-low flux B2MG, AOPP and PCO were all significantly higher than pre-low flux levels (p=0.0002, 0.019, and 0.0002, respectively). Post-low flux B2MG and PCO were significantly higher than post-high flux levels (p 0.0001and p=0.0005, respectively) but no significant difference was observed in AOPP (p= 0.112). Pre-high flux PCO positively correlated with AOPP (p=0.013) and B2MG (p= 0.01). Post-high flux PCO positively correlated with B2MG (p=0.036). Conclusion: High flux hemodialysis results in the reduction of serum beta-2 microglobulin and protein carbonyl whereas advanced oxidation protein products are not affected. On the other hand, low flux hemodialysis is associated with increased levels of the three markers. High flux hemodialysis thus allows better removal of uremic toxins than low flux hemodialysis.