Selective adsorption of homocysteine using an HFR-ON LINE technique.

HFR-ON LINE (double chamber HDF with reinfusion of ultrafiltrate regenerated through a charcoal-resin cartridge) is a novel method which combines the processes of diffusion, convection, and adsorbance. We have investigated the effect of such a treatment on the homocysteine (Hcy) levels in ten patients with a mean Hcy level of 57.6 micromol/L (range 24.1-119.7 micromol/L). We have measured the Hcy, folate, and vitamin B12 predialysis and postdialysis, and in the ultrafiltrate precartridge and postcartridge at 10, 120, and 240 min. The mean Hcy levels were 57.6 and 35.3 micromol/L (range 9.9-80.3 micromol/L) (P = 0.005) predialysis and postdialysis, respectively, while folate and vitamin B12 were unchanged. Precartridge and postcartridge Hcy levels were 11.6 vs. 2.5 micromol/L (P = 0.005), 9.3 vs. 3.9 micromol/L (P = 0.005), and 7.7 vs. 4.6 micro mol/L (P = 0.012) at the three time points considered, while folate and vitamin B12 were essentially undetectable. These preliminary data, which need confirmation in a long-term study, seem to indicate that HFR-ON LINE is able to reduce Hcy levels not only through a likely reduction of uremic toxins, but also through an actual removal of Hcy by adsorbance onto the charcoal-resin cartridge.