Kinetics of Beta2-Microglobulin with Hemodiafiltration and High-Flux Hemodialysis

What is it about?

There is much interest in the potential clinical benefits of adding hemodiafiltration to high-flux hemodialysis. The main benefit is believed to lie in better removal of large molecular weight substances that are uremic toxins, such as beta-2-microglobulin, with molecular weight 11,800 daltons. However, in randomized comparisons of hemodiafiltration vs. high-flux hemodialysis, the predialysis serum beta-2-microglobulin levels did not seem to be markedly altered. We formulated a kinetic model of beta-2-microglobulin removal that allowed us to assess the potential impact of hemodiafiltration on serum beta-2-microglobulin levels. We found that even high-dose hemodiafiltration, giving 25+ liters of replacement fluid in postdilution mode, would be expected to lower predialysis serum beta-2-microglobulin levels by about 10% and time-averaged concentrations by about 17%. The model suggested that this amount of lowering of beta-2 microglobulin concentration was similar to the amount of lowering by persistence of 1.35 ml/min of residual kidney function.

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