[HFR vs HDF-ON line: plasmatic amino acids loss evaluation]

The high convection dialytic techniques, such as hemodiafiltration (HDF), can cause the loss of important molecules such as growth factors, vitamins and amino acids. Hemodiafiltration reinfusion (HFR) is an HDF on-line process, using a sipping cartridge, able to remove uremic toxins and give back a "repaired" ultra-filtrate to the patient. We aimed to establish the plasmatic amino acid levels before and after dialysis in HFR vs. HDF on-line, with scrupulous attention to branched chain amino acids (BCAA) such as isoleucine, leucine and valine. These amino acids, often present with low plasmatic levels in hemodialyzed patients, seem to be related to a picture of malnourishment.

Eleven male patients on bicarbonate dialysis, for at least 1 yr, were evaluated (average dialytic age = 88 months, /average age = 67 yrs), with good dialytic efficiency and body mass levels, randomized in HFR or HDF on-line (filter PAN AN 69) for 1 week of treatment, respectively. The different results of each method were controlled for the same patient. Blood samples were taken before and after dialysis in each 2nd hemodialytic weekly session. Total amino acids, essential, non-essential and BCAA were determined by gas-chromatography.

There was no difference detected in pre-dialytic plasmatic levels of analyzed amino acids between the two groups. In post-dialysis, HDF patients demonstrated a total essential, non-essential amino acid and BCAA higher loss rate, compared to HFR patients. Post-dialysis amino acid level averages were: total amino acids in HDF 1852 +/- 302.6 micromol/L, in HFR 2395 +/- 492.8 micromol/L (p = 0.018); essential amino acids in HDF 428.8 +/- 118.2 micromol/L, in HFR 510.3 +/- 129.3 micromol/L (p = 0.022); non-essential amino acids in HDF 1176 +/- 213 micromol/L, in HFR 1546 +/- 339.2 micromol/L (p = 0.01); BCAA in HDF 242.7 +/- 83.42 micromol/L, and in HFR 286.7 +/- 89.9 micromol/L (p = 0.03).

Since low plasmatic BCAA levels are related to anorexia and malnourishment, the loss of these amino acids can be important in the dialytic technique choice. HFR can offer an outstanding advantage, combining a high convection treatment with medium molecule removal, without compromising physiologic molecule loss.