Correlation of beta-2-microglobulin concentration changes to changes of distribution volume

Plasma and ultrafiltrate beta-2-microglobulin (B2M) concentrations were determined during hemofiltration (HF) and hemodialysis (HD) in order to evaluate elimination kinetics of B2M. Calculations were done on the basis of plasma-water-concentrations (PWC). Elimination of B2M during HF follows first order kinetics (r = 0.97) and the volume of B2M distribution was calculated to be 17 +/- 2% of body weight. This reflects extracellular volume (ECV). Changes of ECV in HD were induced by weight loss and further provoked by fluid shifts from intra- to extracellular volume and vice versa induced by varying dialysate sodium concentration. These ECV changes were followed by determining inuline in plasma and total dialysate. Changes of B2M concentration correlate well to changes of ECV (r = 0.98). Thus intratreatment concentration changes of B2M in cuprophane dialysis reflect simultaneous changes of B2M distribution volume. This does not exclude the possibility of B2M generation stimulated by dialysis, but proving such effects in vivo will be difficult because of multiple variants, that must be controlled.