Evaluation of non-linear and linear mathematical models for creatinine and glucose fitting in peritoneal dialysis

Four non-linear and five linear models for predicting the creatinine dialysate/ plasma ratio (CRD/P) and the glucose dialysate/initial concentration ratio (GLD/D0) were evaluated in a group of 31 patients on peritoneal dialysis and subjected to the peritoneal equilibration test (PET 3.86%, 240'). PET results and classification were compared to obtain a definition of patient peritoneal transport characteristics. The monomolecular and rectangular hyperbola non-linear models, the Lineweaver-Burk, Hanes-Woolf and Dadone linear transformations were considered for the CRD/P fitting. A monoexponential and two-exponential decay plus the semilogarithmic transformations were considered for the GLD/ D0. These models are simple, accurate and functionally homogeneous. Further studies are advisable however on the individual peritoneal transport classification, since approximately 30% of the patients were in different categories for CRD/P and GLD/D0 and the fittings do not give better classification results.