Removal of beta-2-microglobulin by diffusion alone is feasible using highly permeable dialysis membranes

Techniques of filtration with high flux dialysis membranes are capable of easily removing beta-2-microglobulin (beta-2-M) (MW: 11,800) from renal failure patients. However, hemodialysis is preferred as a method of removing beta-2-M in terms of cost and operation. The present study elucidates the permeability characteristics for beta-2-M of newly developed cellulosic and synthetic polymer membranes for hemodialysis to determine the diffusive clearance for beta-2-M. The authors did dialysis experiments with 3H-labeled water and 125I-labeled beta-2-M to obtain the solute permeability of cellulosic and synthetic polymer membranes. Radioactivity of a single hollow fiber after dialysis experiments for predetermined periods was measured in a gamma counter. Through analysis of radioactivity data, they obtained solute permeability data, from which diffusive clearance for beta-2-M was calculated. With wet cellulose triacetate membranes, values for inside diameter, wall thickness, and water content were 205 +/- 10 microns (N = 100), 12.4 +/- 1.5 microns (N = 200), and 78 vol%, respectively. The cellulose triacetate membranes had a solute permeability for beta-2-M of (4.12 +/- 1.83) x 10(-5) cm/sec (N = 25) and a pure water permeability of 60 ml/m2/hr/mmHg. Diffusive clearance for beta-2-M was calculated to be 39 ml/min at a plasma flow rate of 160 ml/min and a dialysate flow rate of 500 ml/min. The diffuse clearance of capillary dialyzers composed of regenerated cellulose and synthetic polymer membranes ranged from 23 to 19 ml/min.(ABSTRACT TRUNCATED AT 250 WORDS)