[The peritoneal transport type might be distinctive among different Mexican populations on CAPD]

The peritoneal equilibration test (PET), standardized by Twardowski et al. more than 20 years ago, is the most common test to classify peritoneal transport. Some reference values from Mexican population were established in the Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán (INCMNSZ) 10 years ago. The aims of this study were to evaluate the peritoneal transport in a population from the west of Mexico, and compare results with those obtained in the studies of Twardowski and the INCMNSZ.

Cross-sectional study, performed in 156 patients. All consecutive CAPD patients to whom a PET was performed between January 2000 and January 2004 were included. Each patient had a standard PET consistent on infusion of a freshly 2L dialysis exchange at 2.5% after drainage of the previous nocturnal exchange; 3 dialysis aliquots at 0, 2 and 4 hours, and a blood sample at 2 hours, are obtained after infusion. Results were compared to those reported by Twardowski and INCMNSZ.

From the total of patients, 48% were diabetics and 62% were men. Mean age was 46 +/- 16 years and body surface area was 1.70 +/- 0.23 m2. There were no differences between groups regarding diabetes and peritonitis. Time on dialysis was shorter in our study than in the INCMNSZ (14.6 +/- 17.8 vs. 20.8 +/- 21.4 months; p < 0.05). Compared to those from Twardowski and INCMNSZ, creatinine D/P ratios at 0, 2 and 4 h of our study were higher, whereas D/D0 ratios at 2 and 4 h, and PET drained volume, were lower. Using reference values obtained in the present study, high transport (H) was present in 18%, high average (HA) in 33%, low average (LA) in 34% and low (L) in 15%, whereas employing the INCMNSZ reference values, H was present in 23%, HA in 36%, LA in 33% and L in 8%.

Patients from this studied population had mean peritoneal transport values higher than those obtained in other studies, including Mexican values. Ideally, it is recommendable to determine reference values in all peritoneal dialysis centers, as extrapolating results from other regions may lead to errors in diagnosing the peritoneal transport type.