Peritoneal equilibration curve for beta-2-microglobulin (B2M) in CAPD patients.

To evaluate B2M removal during CAPD, the equilibration curve was determined in 9 CAPD patients (aged 67.9 +/- 6.5 years, treated for 19.0 +/- 17.4 months). The study was carried out on 2 consecutive days using 1.36% (day 1) and 3.86% (day 2) dextrose dialysis solutions for 6 hours each day. The B2M plasma value was the mean of 4 samples taken at the start and after 2, 4 and 6 hours. Dialysate values were determined on 3 ml samples taken every 30 minutes. The curve was fitted for dialysate to plasma B2M ratio (D/P) versus time to define the B2M equilibration curve. Our results showed that the value had a linear regression with both types of solution in all patients. The D/P B2M ratio was linear during the 6 hours of dwell time. Furthermore, there was no significant difference between the 2 solutions used. In conclusion, standard CAPD allows a low but constant B2M removal. An increase or a reduction in dwell time do not seem to have any influence on the B2M removal, which could be improved by methods other than varying dwell time and/or solution osmolarity.