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Titolo	Resistance to intercompartmental mass transfer limits beta(2)-microglobulin removal by post-dilution hemodiafiltration.
Autore	R.A. Ward, T. Greene, B. Hartmann, W. Samtleben
Referenza	Kidney International 2006; 69 (8): 1431-1437 - doi:10.1038/sj.ki.5000048
Contenuto	Although clearance of beta(2)-microglobulin is greater with hemodiafiltration than with high-flux hemodialysis, beta(2)-microglobulin concentrations after long-term hemodiafiltration are only slightly less than those obtained with high-flux hemodialysis. Resistance to beta(2)-microglobulin transfer between body compartments could explain this observation. beta(2)-Microglobulin kinetics were determined in patients receiving on-line post-dilution hemodiafiltration for 4 h with 18 l of filtration. Plasma beta(2)-microglobulin concentrations were measured during and for 2 h following hemodiafiltration and immediately before the next treatment. The filter clearance of beta(2)-microglobulin was determined from arterial and venous concentrations. The beta(2)-microglobulin generation rate was calculated from the change in the plasma concentration between treatments. The intercompartmental clearance was obtained by fitting the observed concentrations to a two-compartment, variable volume model. The plasma clearance of beta(2)-microglobulin by the filter was 73+/-2 ml/min. Plasma beta(2)-microglobulin concentrations decreased by 68+/-2% from pre- to post-treatment (27.1+/-2.2-8.5+/-0.7 mg/l), but rebounded by 32+/-3% over the next 90 min. The generation rate of beta(2)-microglobulin was 0.136+/-0.008 mg/min. The model fit yielded an intercompartmental clearance of 82+/-7 ml/min and a volume of distribution of 10.2+/-0.6 l, corresponding to 14.3+/-0.7% of body weight. Hemodiafiltration provides a beta(2)-microglobulin clearance of similar magnitude to the intercompartmental clearance within the body. As a result, intercompartmental mass transfer limits beta(2)-microglobulin removal by hemodiafiltration. This finding suggests that alternative strategies, such as increased treatment times or frequency of treatment, are needed to further reduce plasma beta(2)-microglobulin concentrations.Kidney International (2006) 69, 1431-1437. doi:10.1038/sj.ki.5000048; published online 4 January 2006.
Data	20.04.2006

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