Objective: To evaluate the peritoneal clearance of middle molecules in comp
arison with the peritoneal clearance of small molecules in incremental peri
toneal dialysis (PD).
Study Design: Peritoneal clearances of creatinine and beta (2)-microgloblul
in (B2M) were compared in 57 continuous ambulatory PD patients on full dose
of 4 exchanges, and 54 incremental PD patients with 2 or 3 exchanges over
24 hours. Clearances were also compared when there were changes in the PD r
egimen, such as in the number of exchanges and the duration of the dwell ti
Setting: Tertiary-care university hospital.
Results: Peritoneal creatinine clearance increased almost linearly with the
increase in the number of exchanges. In contrast, peritoneal clearance of
B2M was 9.1 +/-3.6 L/week, 8.8 +/-4.4 L/week, and 7.9 +/-2.5 L/week with 2,
3, and 4 exchanges, respectively, per day, amounts that were not different
from each other. Peritoneal clearance of B2M did not change when there was
an increase in the number of dialysate exchanges from 2 to 3 and from 3 to
4 over a period of 24 hours; whereas the peritoneal clearance of creatinine
increased. Peritoneal clearance of B2M almost doubled, from 5.4 +/-2.7 L/w
eek with 2 exchanges over 12 hours per day, to 9.5 +/-4.4 L/week with the s
ame 2 exchanges over 24 hours. The creatinine clearance did not change.
Conclusion: In contrast to peritoneal clearance of small molecules, such as
creatinine, which was dependent on the number of dialysate exchanges, peri
toneal clearance of middle molecules, such as B2M, depended mainly on the t
otal dwell hours of PD and not on the number of exchanges of peritoneal dia
lysate in incremental PD. This might be another advantage of incremental PD
, since peritoneal clearance of middle molecules in incremental PD over 24
hours can be comparable to that in full dose PD.