Loss of Amino Acids Into Dialysate During Hemodialysis Using Hydrophilic and Nonhydrophilic Polyester-Polymer Alloy and Polyacrylonitrile Membrane Dialyzers

During hemodialysis, amino acid loss through the dialysate remained a significant problem and was not clear in some dialyzers; therefore, we investigated amino acid loss with hydrophilic and nonhydrophilic polyester–polymer alloy membranes and polyacrylonitrile membranes. Nine maintenance hemodialysis patients were studied to assess amino acid loss during hemodialysis with the three membranes. Total amino acid losses were 85.7 ± 27.2 mg/L, 83.3 ± 16.1 mg/L, and 72.1 ± 22.5 mg/L with the hydrophilic, nonhydrophilic polyester–polymer alloy, and polyacrylonitrile membranes, respectively. Amino acid losses were greater with the hydrophilic membrane compared with the polyacrylonitrile membrane for ornithine (2.0 ± 0.6 vs. 1.4 ± 0.4 mg/L, P = 0.025), phenylalanine (2.4 ± 0.9 vs. 1.8 ± 0.8 mg/L, P = 0.012), and tryptophan (0.6 ± 0.2 vs. 0.4 ± 0.2 mg/L, P = 0.023). Amino acid losses were greater with the nonhydrophilic membrane than with the polyacrylonitrile membrane for ornithine (2.0 ± 0.4 vs. 1.4 ± 0.4 mg/L, P = 0.017), phenylalanine (2.3 ± 0.5 vs. 1.8 ± 0.8 mg/L, P = 0.018), tryptophan (0.7 ± 0.2 vs. 0.4 ± 0.2 mg/L, P = 0.003), and cystine (3.2 ± 0.7 vs. 2.0 ± 0.7 mg/L, P = 0.005). In conclusion, greater losses of ornithine, phenylalanine, tryptophan, and cystine were observed with polyester–polymer alloy than with polyacrylonitrile membranes during hemodialysis. Constant attention should be paid to the amino acid loss profile to improve nutritional control in hemodialysis patients.