Factors affecting beta 2-microglobulin plasma concentration during hemodialysis

Area of Science:

• Nephrology
• Biomaterials Science
• Clinical Chemistry

Background:

• Beta-2 microglobulin (beta 2m) is a protein that accumulates in patients with chronic kidney disease undergoing hemodialysis.
• The accumulation of beta 2m is associated with the development of amyloidosis.
• Dialyzer membrane properties significantly influence the removal of solutes like beta 2m during hemodialysis.

Purpose of the Study:

• To compare the efficacy of four different hemodialysis membranes (cuprophan, ethylenevinylalcohol, polyacrylonitrile, and polysulfone) in removing beta 2m.
• To investigate the mechanisms of beta 2m removal, including filtration and adsorption, across these membranes.

Main Methods:

• Ten hemodialysis patients were sequentially treated with cuprophan (CU), ethylenevinylalcohol (EVAL), polyacrylonitrile (AN-69), and polysulfone (PSP) dialyzers.
• Plasma and dialysate beta 2m concentrations were measured using radioimmunoassay.
• In vitro adsorption studies were performed using I-125-labelled beta 2m and the different membrane materials.

Main Results:

• Cuprophan (CU) dialyzers showed no significant change in plasma beta 2m concentration.
• Ethylenevinylalcohol (EVAL), polyacrylonitrile (AN-69), and polysulfone (PSP) dialyzers resulted in a significant decrease in plasma beta 2m.
• High-permeability membranes (AN-69 and PSP) demonstrated substantial beta 2m recovery in the dialysate, indicating efficient filtration.
• In vitro studies showed AN-69 had the highest adsorption capacity (13%), followed by CU (9%), PSP (7%), and EVAL (4%).

Conclusions:

• Polysulfone (PSP) membranes achieve beta 2m clearance primarily through mass transport (filtration).
• Polyacrylonitrile (AN-69) membranes remove beta 2m via both adsorption and filtration.
• High-flux membranes are more effective in reducing beta 2m levels during hemodialysis compared to low-flux membranes.