Rapid decline of residual renal function in patients on automated peritoneal dialysis.

OBJECTIVE: To determine the effect of peritoneal dialysis modalities such as nightly intermittent peritoneal dialysis (NIPD), continuous cyclic peritoneal dialysis (CCPD), and continuous ambulatory peritoneal dialysis (CAPD) on residual renal function.

DESIGN: A six-month prospective, nonrandomized comparison study.

SETTING: Outpatient CAPD unit of a university hospital.

PARTICIPANTS: Eighteen end-stage renal disease patients treated by peritoneal dialysis (8 by NIPD, 5 by CCPD, and 5 by CAPD).

INTERVENTIONS: Samples from the total dialysate, blood, and 24-hour urine collection were obtained monthly.

MEASUREMENTS: Urea, creatinine, and beta2-microglobulin concentrations were measured. Renal and peritoneal clearances of each substance and KT/V urea were calculated. Residual renal function (RRF) was estimated by renal creatinine clearance (RCcr).

RESULTS: No significant differences in age, sex, and primary renal disease among the three groups were noted. In all groups, anemic and hypertensive states were controlled identically, and mean weekly total (renal + peritoneal) KT/V urea (over 2.1/wk) and total creatinine clearance (over 60 L/wk/1.73 m2) were maintained during the whole experimental period. Starting mean RCcr was near 4.0 mL/min/1.73 m2 in all groups. Thereafter, a rapid and significant decline in RRF was demonstrated on NIPD and CCPD. The declining rates of RCcr values at 6 months after starting NIPD and CCPD were -0.29 and -0.34 mL/min/month, respectively, which were much greater than those of CAPD (+0.01 mL/min/month).

CONCLUSION: Because of a possibly characteristic progressive loss of RRF in automated peritoneal dialysis (APD), strict regular assessment of RRF should be performed from the start of APD.