In addition to CAPD, various modalities of peritoneal dialysis such as CCPD and NIPD have been introduced recently. The adequacy in these peritoneal dialysis has been evaluated by clearance of small molecular weight solutes such as creatinine(molecular weight 113 Dalton) and urea(molecular weight 60 Dalton). The middle molecular weight solutes(molecular weight 3,000 to 12,000 Dalton) have been regarded as one of the uremic toxins. Relatively larger clearance of middle molecular weight solutes is one of the advantages of CAPD compared with HD. Although peritoneal transport of middle molecular solutes can be different from that of small molecular weight solutes because of its size, there are a few reports about peritoneal transport characteristics and clearance of middle molecular weight solutes in various modalities of PD. We wanted to analyze peritoneal transport characteristics and clearances of middle molecular weight solute in various modalities of peritoneal dialysis in comparison with small molecular weight solutes. To evaluate the potential differences in peritoneal transport characteristics and clearances of middle and small molecules in CAPD, CCPD and NIPD, we compared transport characteristics and clearance of beta2-MG and creatinine. 35 CAPD patients, 9 CCPD patients, 7 NIPD patients were included in the study, who were clinically stable for at least one month without peritonitis. he beta2-MG concentrations in serum and dialysate as measured by radioimmunoassay. Standard peritoneal equilibration test and a weekly peritoneal clearance for creatinine and beta2-microglobulin were used. The results were as follows: 1)Dialysate to plasma ratio of beta2-MG were 0.11+/-0.03, 0.13+/-0.05, 0.10+/-0.02, 0.08+/-0.03, respectively in high(N=6), high average(N=13), low average(N= 14), low(N=7) group according to PET. There were significant differences between high average and low average, high average and low group(p<0.05). Correlation between D/Pbeta2-MG ratio and D/Pcr ratio was significant(spearman's p=0.453, p<0.05). 2)In 35 CAPD patients, peritoneal creatinine and beta2-MG clearance were 48.9, 8.2L/wk, respectively and there was a weak correlation between them (Spearman's p=0.294, p<0.05). 3)The peritoneal creatinine clearance were 48.9, 41.0, 35.9L/wk and beta2-MG clearance were 8.2, 5.5, 4.1L/wk, respectively in CAPD, CCPD and NIPD. The ratio of peritoneal beta2-MG clearance to creatinine clearance were 0.16, 0.14, 0.11, respectively in CAPD, CCPD and NIPD. Peritoneal beta2-MG clearance in APD such as CCPD and NIPD is lesser than that in CAPD. In conclusion, peritoneal transport characteristics for beta2-MG differ from that for creatinine, although peritoneal clearnce for beta2-MG corrleated with that for creatinine. Perioneal clearance for beta2-MG was better in CAPD than in APD.
Creatinine ; Humans ; Molecular Weight ; Peritoneal Dialysis ; Peritoneal Dialysis, Continuous Ambulatory ; Peritonitis ; Plasma ; Radioimmunoassay