Validation of cystatin C-based equations for evaluating residual renal function in patients on continuous ambulatory peritoneal dialysis

Residual renal function needs to be assessed frequently in patients on continuous ambulatory peritoneal dialysis (CAPD). A commonly used method is to measure creatinine (Cr) and urea clearance in urine collected over 24 h, but collection can be cumbersome and difficult to manage. A faster, simpler alternative is to measure levels of cystatin C (CysC) in serum, but the accuracy and reliability of this method is controversial. Our study aims to validate published CysC-based equations for estimating residual renal function in patients on CAPD.