Amino acid losses during hemodialysis with polyacrylonitrile membranes: effect of intradialytic amino acid supplementation on plasma amino acid concentrations and nutritional variables in nondiabetic patients

Background: Malnutrition is highly prevalent in hemodialysis patients. Amin o acid (AA) losses during the dialysis procedure may! be a contributing fac tor. Objectives: The objectives of this study were I) to prospectively evaluate AA losses and their effect on plasma AA concentrations during dialysis with polyacrylonitrile at baseline and after administration of AAs by intradial ysis and 2) to investigate the effects of intradialytic AA supplementation on nutritional status. Design: Seventeen stable patients without diabetes who were receiving hemod ialysis were studied. In the first phase, AA losses were evaluated over 2 w k in 10 patients randomly assigned to receive AA supplementation. AA losses were analyzed during the first week without supplementation and during the second week with AA administration. In the second phase, the patients' nut ritional status was investigated after 3 mo of AA supplementation and was c ompared with those in 7 patients not receiving AAs. Results: Mean ((x) over bar +/- SD) AA losses during a 4-h dialysis session were 12 +/- 2 g; there was a significant decrease in plasma AA concentrati ons (386 +/- 298 mu mol/L for essential and 902 +/- 735 mu mol/L for noness ential AAs). After administration of AAs, the losses increased to 28 +/- 4 g. However, this procedure produced a positive net balance of AAs (10.6 +/- 5.6 g for total AAs), preventing a reduction in plasma concentrations. Aft er 3 mo of AA administration, there was a significant increase in protein c atabolic rate and serum albumin and transferrin. This improvement occurred without any change in the dialysis dose, ruling out the possibility that an increase in dialysis efficiency played a role. Conclusions: Intradialysis adequately provides AA supplements. prevents red uctions in plasma AA concentrations, and favorably affects the nutritional status of patients receiving hemodialysis.