Amino acid losses are lower during pre-dilution on-line HDF than HD of the same Kt/V for urea

Abstract

In this study, we investigated differences in amino acid losses between HD and pre-dilution on-line HDF with equal Kt/V for urea to determine which modality removes less amino acids from extravascular pools and ensures better nutrition. The subjects were patients receiving pre-dilution on-line HDF (n = 10) or HD (n = 10) at this hospital. Dialysis time was 4 h for all patients. In patients on HD, the blood flow rate was 200 mL/min and the dialysate flow rate was 463 ± 29.3 mL/min. In patients on pre-dilution on-line HDF, the blood flow rate was 240 ± 20 mL/min, the dialysate flow rate was 565.0 ± 42.5 mL/min, and the substitution flow rate (substitution volume) was 252.8 ± 26.4 mL/min (57.0 ± 6.0 L). Kt/V for urea was comparable between patients on HD and patients on pre-dilution on-line HDF (1.46 ± 0.25 vs. 1.46 ± 0.31). Amino acid loss and clear space were evaluated. Patients on pre-dilution on-line HDF lost significantly less glutamine and arginine (p < 0.01 and p = 0.032) and significantly less nonessential amino acids (NEAAs) than patients on HD (p = 0.013). They also had significantly lower clear space of total amino acids (TAAs), NEAAs, essential amino acids (EAAs), and branched-chain amino acids (BCAAs) than patients on HD (Total AA p = 0.019, NEAA p = 0.018, EAA p = 0.024, BCAA p = 0.042). When Kt/V for urea is equal, pre-dilution on-line HDF ensures better nutrition than does HD.