Dialysis adequacy indices and body composition in male and female patients on peritoneal dialysis

Abstract

Objectives: Creatinine clearance scaled to body surface area (BSA) and urea KT/V normalized to total body water (TBW) are used as indices for peritoneal dialysis (PD) adequacy. We investigated relationships of indices of dialysis adequacy (including KT/V, KT, clearance, dialysate over plasma concentration ratio) and anthropometric and body composition parameters (BSA, TBW, body mass index (BMI), weight, height, fat mass (FM), and fat-free mass (FFM)) in male and female patients on continuous ambulatory peritoneal dialysis.

Methods: Ninety-nine stable patients (56 males) performed four 24-hr collections of drained dialysate for four dialysis schedules with three daily exchanges of glucose 1.36% and one night exchange of either: 1) glucose 1.36%, 2) glucose 2.27%, 3) glucose 3.86% or 4) icodextrin 7.5%.

Results: KT and dialysate over plasma concentration ratio, CD/CP, for urea and creatinine were similar for males and females and, in general, did not depend on body-size parameters including V (= TBW), which means that the overall capacity of the transport system in females and males is similar. However, after normalization of KT to V or 1.73/BSA yielding KT/V and creatinine clearance, Cl(1.73/BSA), respectively, the normalized indices were substantially higher in females than in males and correlated inversely with body-size parameters, especially in males.

Conclusions: As KT/V depends strongly on body size, treatment target values for KT/V should take body size and therefore also gender into account. As KT is less influenced by body size, body composition and gender, KT should be considered as a potential auxiliary index in PD.

Keywords: KT/V; Peritoneal dialysis adequacy; body composition; clearance; creatinine; gender; urea.

Figure 1 —

Adjusted r² of multivariate linear regression for weekly, total urea KT/V and KT predicted by the model containing body surface area (BSA), total body water (TBW), body mass index (BMI), weight, height, fat mass (FM) and fat-free mass (FFM), separately, with adjustment to age, time on PD, mean protein intake and fluid schedule, in female and male patients (^* p<0.05, ^** p<0.01, ^*** p<0.001, where p values describe statistical significance of adjusted r²).

Figure 2 —

Adjusted r² of multivariate linear regression for weekly, total creatinine KT/V and KT predicted by the model containing body surface area (BSA), total body water (TBW), body mass index (BMI), weight, height, fat mass (FM) and fat-free mass (FFM), separately, with adjustment to age, time on PD, mean protein intake and fluid schedule, in female and male patients (^* p<0.05, ^** p<0.01, ^*** p<0.001, where p values describe statistical significance of adjusted r²).