Cellulose Acetate and Cuprophane for Hemodialysis: Effects on Protein Catabolic Rate

Dr. N.R. Robles, Apdo. 20054, E-06080 Badajoz (Spain) Dear Sir It has been suggested that in dialyzed ure-mic patients the protein catabolic rate (PCR) is directly dependent upon the amount and type of hemodialysis (HD) treatment they receive as measured by the normalized whole-body urea clearance (Kt/V). Different treatment methods may influence the interrelationship of PCR and Kt/V in different ways: to obtain an equal PCR, a higher Kt/V must be prescribed when using cellulosic membranes for HD [1]. The most obvious explanation for this is related to the different solute clearance profiles that exist with synthetic membranes and cellulosic ones. On the other hand, bio-compatibility may influence the nutritional problems of HD [2]. A clinical trial has been performed in which the effects of two cellulosic membranes (cuprophane, CU, and cellulose acetate, CA) with similar permeability and different biocompatibility [3, 4] on the PCR were assessed. Forteen stable patients with chronic renal failure on HD treatment for more than 6 months were included. The patients received HD first by dialyzers containing CU membranes or by CA hollow-fiber dialyzers. Each of two dialyzers was used for 78 consecutive HD treatments over a period of 6 months. The studies were carried out every 2 months spanning a total of 12 months. Blood samples were collected from the arterial line at the start and at the end of the midweek session. Kt/V, time-averaged concentration of urea (TAC) and PCR were estimated using a simplified model [5]. No differences were found for Kt/V between CU and CA HD (1.02 ± 0.12 vs. 1.06 ± 0.11). TAC values were significantly lower when patients were dialyzed by CU membranes (CU 54.6 ± 13.9, CA 63.6 ± 17.3 mg/dl, p < 0.05). Also PCR values were lower when patients were dialyzed by CU dialyzers (CU, 1.04 ± 0.28, CA 1.25 ± 0.37 mg/kg/day, p < 0.01). There was a trend toward an increase in total protein when using CA dialyzers (CU 6.93 ± 0.32, CA 7.07 ± 0.35 g/dl, n.s.). A slight increase in albumin was observed during treatment with CA membranes (CU 4.33 ± 0.19, CA 4.42 ± 0.22 g/dl, n.s.). A linear correlation between Kt/V and PCR existed for both membranes (CU, r = 0.35, n = 42, p < 0.05; CA, r = 0.41, n = 42, p < 0.01). The slope of the regression line for the dialyzers containing the CA membrane was greater (CA 1.19, CU 0.83), although this difference was not significant. In dialyzed uremic patients who do not have extraneous factors (e.g. malignant disease), the PCR seems to be directly dependent upon the amount and type of HD treatment they receive as