Impact of high-flux/high-efficiency dialysis on folate and homocysteine metabolism.

High-flux/high-efficiency (HF/HE) dialysis may have detrimental effects on micro-nutrients and water-soluble vitamins, such as vitamin B6, whose levels are lowered. Folate deficiency may increase cardiovascular risk through an increase in homocysteine (Hcy) serum levels. We therefore investigated the effects of dialysis with a high-flux (HF) membrane on folate and Hcy metabolism. Twelve patients without any folate supplementation, receiving dialysis with a low-flux membrane prior to the study (TO), were switched to dialysis using a HF triacetate membrane for four months (T1, T2, T3, T4) and received an oral daily folate supplementation during the two last months (T3, T4). Mean predialysis plasma folate levels fell dramatically after one month of HF dialysis (T1) and remained significantly lower than the initial level (p<0.05) at T2. Hcy concentrations were high in all patients at TO (mean 47.3 +/- 17.6 microM, normal range 5 to 15 microM). They did not change during the first two months of the study but dropped steeply after the beginning of oral folate supplementation. Folate supplementation should be used in HF/HE dialysis to avoid folate depletion. The combination of folate supplementation and HF/HE may lower Hcy levels and reduce cardiovascular morbidity and mortality in these patients.