Dialysate copeptin and peritoneal transport in incident peritoneal dialysis patients

PURPOSE: Systemic and intraperitoneal inflammation are characteristic features of patients with end-stage renal disease undergoing chronic peritoneal dialysis (PD). Arginine vasopressin (AVP) and its surrogate marker copeptin play important roles in many pathophysiological processes in chronic kidney disease. The aim of this study was to assess if copeptin concentrations in plasma and dialysate were related to peritoneal transport parameters and residual renal function (RRF) in incident PD patients. METHODS: In 37 clinically stable incident PD patients (mean age 50 years, 68% women, 32% diabetes), a 4 h peritoneal equilibration test (PET) was performed 4-6 weeks after the onset of PD. Plasma (at 2 h of PET) and dialysate (at 4 h) concentrations of copeptin, high-sensitivity C-reactive protein and interleukin-6 (IL-6) were determined. RESULTS: Plasma (80.7 ± 37.3 pg/mL) and dialysate (33.2 ± 18.0 pg/mL) concentrations of copeptin were correlated (Rs = 0.52, p = 0.001). Plasma and dialysate copeptin concentrations were negatively correlated with renal function as assessed by renal Kt/V (Rs = - 0.38; p = 0.021 and Rs = - 0.33; p = 0.047, respectively). At PET, dialysate copeptin negatively correlated with D/P creatinine (Rs = - 0.35, p = 0.033), and positively with D/D0 glucose (Rs = 0.33, p = 0.045) and ultrafiltration (Rs = 0.37, p = 0.024). Multivariate analysis showed that low dialysate copeptin (β = -0.30, p = 0.049) and high dialysate IL-6 (β = + 0.40, p = 0.012) were independent determinants of higher D/P creatinine. CONCLUSIONS: Dialysate copeptin was negatively associated with D/P creatinine in incident PD patients suggesting a potential influence of copeptin or AVP on peritoneal solute transport rate that might involve vasoactive mechanisms.