Beta 2-microglobulin kinetics during haemodialysis and haemofiltration.

Since the identification of beta 2-microglobulin as a major component of 'dialysis amyloid', concern about its removal by different dialysis methods has been raised. Haemodialysis with regenerated cellulose membranes increases serum beta 2-microglobulin by 10-15%. Serial measurements show a very early increase during cuprophan haemodialysis, the mechanism of which is as yet unknown. After cuprophan haemodialysis, serum values return to the initial pretreatment concentrations by the time of the next haemodialysis. In contrast to regenerated cellulose, dialysis with polycarbonate lowers serum beta 2-microglobulin by 8%, and dialysis with polysulphone by 53%. As opposed to cuprophan, after polysulphone haemodialysis the serum concentrations have not returned to the initial pretreatment levels within 48 h. Comparison of beta 2-microglobulin removal using the same polysulphone membrane for haemodialysis and haemofiltration shows that beta 2-microglobulin is more effectively removed by convection than by diffusion when both treatment modes are matched for blood flow and urea clearance. Therefore, in contrast to haemodialysis with regenerated cellulose membranes, where a transient, intradialytic release of beta 2-microglobulin is induced, significant removal is observed using higher permeable membranes. These findings may have implications for the generation of 'dialysis amyloid'.