High peritoneal clearance of small molecules did not provide low serum beta2-microglobulin concentrations in...

Although early reports demonstrated that serum beta(2)-microglobulin (s-beta(2)m) concentrations in patients on peritoneal dialysis (PD) were lower than those in patients on hemodialysis (HD), more recent studies demonstrated lower s-beta(2)m concentrations in HD patients treated mainly with high-flux synthetic membranes. We therefore compared s-beta(2)m concentrations between patients on PD and on HD, and also analyzed the relationship between s-beta(2)m concentrations and other parameters in patients on PD.

We investigated 24 patients who had been undergoing PD [11 on continuous ambulatory peritoneal dialysis, 13 on continuous cycling peritoneal dialysis] for 4.3 +/- 2.7 years, and 24 patients who had been undergoing HD with high-flux synthetic membranes for 6.1 +/- 3.2 years. Concentrations of s-beta(2)m in the PD patients were compared to concentrations in the HD patients. In patients on PD, we also analyzed the relationship between s-beta(2)m concentration and other parameters, including residual renal function, total weekly Kt/V urea, total weekly creatinine clearance (CCr), and dialysis schedules.

We found no significant difference in s-beta(2)m concentrations between the PD and HD patients (33.6 +/- 10.4 mg/L vs 30.3 +/- 10.5 mg/L respectively). Concentrations of s-beta(2)m in PD patients rose with PD duration and were significantly inversely correlated with residual renal function (r = -0.71, p < 0.0001). Unexpectedly, concentrations of s-beta(2)m in anuric PD patients rose as peritoneal CCr increased. And most of the patients with high s-beta(2)m levels fell into the high or high-average transport categories according to a peritoneal equilibration test.

Concentrations of s-beta(2)m in patients on PD did not differ significantly from concentrations in HD patients who were using high-flux synthetic membranes. The contribution of residual renal function to removal of beta(2)m was more important than the contribution of peritoneal clearance. High peritoneal clearance of small molecules did not result in low s-beta(2)m concentrations, especially in anuric patients with accelerated peritoneal permeability.