EFFECT OF DIFFERENT MEMBRANES ON AMINO-ACID LOSSES DURING HEMODIALYSIS

Background. We analysed amino-acid losses during haemodialysis, their influence on plasma amino-acid concentration, and their possible effec ts on nutritional state. Methods. Five patients were dialysed with thr ee membranes: cuprophan (CUP), polysulphone (PS), and polyacrylonitril e AN69 (PAN). We compared anthropometric and biochemical parameters af ter 6 months in patients dialysed with CUP respect to patients with PA N. Results. Total losses of amino acids were higher with PAN than with PS and CUP (6.1 +/- 2.3 vs 3.8 +/- 1.3, P<0.05, and 3.7 +/- 1.3 g/ses sion, P<0.01 respectively). Losses of essential amino acids (EAA) and nonessential amino acids (NEAA) were also higher with PAN respect to P S and CUP (1.8 +/- 0.8 vs 1 +/- 0.3 and 0.8 +/- 0.3, and 4.3 +/- 1.6 v s 2.8 +/- 1 and 2.9 +/- 1.1 g/session, P<0.05). The percentage reducti on for plasma EAA and NEAA were lower with CUP respect to PS and PAN ( 11 +/- 5% and 20 +/- 14% vs 25 +/- 10% and 33 +/- 11%, and 30 +/- 11% and 25 +/- 17% respectively, P<0.05). There was no difference in the n utritional state between patients with CUP and PAN. However, plasma va line in patients with PAN was lower than in those with CUP (1.88 +/- 0 .12 vs 2.13 +/- 0.32 mg/dl) and almost reached statistical significanc e. Conclusions. New synthetic membranes are advantageous with respect to conventional ones, but a disadvantage is the higher amino-acid loss es, especially with polyacrylonitrile. Long-term studies are necessary to evaluate the impact of amino-acid losses on nutritional state in p atients dialysed with these membranes.