Long-term reduction of plasma homocysteine levels by super-flux dialyzers in hemodialysis patients

BACKGROUND: Hyperhomocysteinemia is an independent risk factor for cardiovascular disease in chronic hemodialysis (CHD) patients. Treatment with folic acid normalizes total homocysteine (tHcy) in only a minority of the patients. The present investigation has been conducted to study the influence of various dialyzers with different flux characteristics on the reduction of tHcy in the long term.

METHODS: Total Hcy, folate, vitamin B6, vitamin B12, and albumin levels were assessed prospectively in 10 patients undergoing HD with high-flux polysulfon (PS; F 60) and 20 patients with super-flux dialyzers (N = 10 PS, F 500S; N = 10 CTA, Tricea 150G). Blood samples were collected before hemodialysis both at the beginning of the study and after 12 weeks.

RESULTS: At baseline, all the groups showed similar tHcy levels. During high-flux dialysis, tHcy remained stable. In contrast, during dialysis with both super-flux modalities, tHcy decreased significantly (F 500S week 1, 29.6 +/- 9.9 micromol/L, and week 12, 21.5 +/- 8.5 micromol/L, P = 0.007; Tricea 150G week 1, 24.4 +/- 8.7 micromol/L, and week 12, 15.3 +/- 3.7 micromol/L, P = 0.008). The difference between high-flux and super-flux dialyzers was highly significant (mean: high-flux increase 15.6%, super-flux decrease 33. 3%, P = 0.001). Multivariate analysis showed a significant effect of super-flux dialysis on tHcy (P = 0.001), independently of the previously mentioned variables.

CONCLUSIONS: Our findings clearly show that both types of super-flux dialyzers reduced tHcy significantly. As the molecular weight of free homocysteine is less than 268 D, the most likely explanation seems to be the removal of uremic toxins with inhibitory activities against enzymes involved in the extrarenal homocysteine metabolism.