Peritoneal function tests: usefulness of simplified methods

The Peritoneal Equilibration Test (PET) as standardized by Twardowski (T) and simplified Mass Transfer Coefficients (MTC) as per Garred (G) and Krediet (K) have been employed in our patients to assess: 1) the reproducibility of results, 2) correlation between methods, and 3) usefulness of patient categorization by simplified methods in contrast to PET patterns. We have performed 29 standardized PET (Dianeal 2.5%) in 24 stable CAPD patients. We have collected dialysate samples at 0, 30, 60, 120, 180 and 240 minutes. With this data we were able to calculate the dialysate/plasma ratio for PET, MTC as per Garred and MTC as per Krediet. Our results were not significantly different from data reported by the original authors, except for PET D/P urea at 240': 0.91 +/- 0.07(T) vs. 0.87 +/- 0.08 (our), p < 0.05. In our patients, good correlation was found between PET and MTC for urea, creatinine, and glucose, using both formulae (G and K). Patient categorization as High, High Average, Low Average, and Low by MTCs can well predict PET categorization with acceptable sensitivity and good specificity. We conclude there is good reproducibility of the methods. There is also a close correlation between PET, K and G methods for solute transport evaluation and patient categorization. Simplified methods can be substituted for the more complex ones.