A SIMPLE ASSESSMENT OF PERITONEAL TRANSPORT IN STABLE CONTINUOUS AMBULATORY PERITONEAL-DIALYSIS PATIENTS

We studied the peritoneal transport properties in 175 stable continuou s ambulatory peritoneal dialysis (CAPD) patients seeking a simple and handy assessment of peritoneal permeability to small solutes. Measurem ent of creatinine in biological fluid was known to suffer from interfe rence by high glucose concentration in the sample. Furthermore, the in terference is also affected by the creatinine concentration of the spe cimen. Peritoneal transport properties were studied by determining the dialysate to plasma ratio of creatinine concentration (D/P) at the fo urth hour of the peritoneal equilibration test, and the mass transfer area coefficient of creatinine (MTACCr) or glucose (MTACGlu). The rati o of glucose concentration in peritoneal dialysate effluent (PDE) at 4 and 0 h (G4/G0) was examined and compared with various peritoneal par ameters. There were significant logarithmic correlations between D/P o r G4/G0 with MTACCr (r = 0.96 and 0.79, respectively, p < 0.0001). The correlation between G4/G0 and D/P was linear (r = -0.82, p < 0.0001). A fairly good agreement was present between G4/G0 and D/P by Bland an d Altman's method. The bias was -0.93% with 95% confidence interval -2 3.29% to 21.43% of the measured value. Systematic error was found when D/P or G4/G0 were compared with MTACCr. D/P under estimated MTACCr in the high range. The reverse happened for G4/G0. Net ultrafiltration ( NUF) also correlated with MTACCr, D/P and G4/G0 (r = -0.32, p < 0.001; -0.26, p < 0.01; and 0.16, p < 0.05, respectively. In conclusion, the use of G4/G0 as a measure of peritoneal transport in CAPD is an accep table alternative to D/P. It is highly reproducible and avoids correct ion of interference when creatinine transport parameters are measured. Because of the logarithmic relations of G4/G0 (or D/P) with MTACCr, t he former should not be directly converted to MTACCr. Such a simple me asure of peritoneal permeability is, however, most convenient for seri al monitoring and can be useful to detect early loss of ultrafiltratio n or solute clearance.