# Peritoneal and renal DKK3 clearance in peritoneal dialysis

## TL;DR

This study explores how DKK3, a biomarker related to kidney function, behaves in peritoneal dialysis patients, revealing its patterns in blood, urine, and dialysate.

## Contribution

The study is the first to report DKK3 excretion into the peritoneal cavity and its relationship with dialysis techniques and RAAS blockade.

## Key findings

- DKK3 concentrations were highest in serum, followed by urine, with significantly lower levels in dialysate.
- RAAS blockade decreased urinary DKK3 but not serum or peritoneal DKK3.
- CAPD increased peritoneal DKK3 in a volume-dependent manner compared to creatinine.

## Abstract

Urinary Dickkopf 3 (DKK3) excretion is a recently established biomarker of renal functional development. Its excretion into the peritoneal cavity has not been reported. We here studied DKK3 in peritoneal dialysis.

DKK3 was assessed in serum, urine and dialysate in a prevalent adult peritoneal dialysis cohort and its concentration analyzed in relation to creatinine and clinical characteristics.

Highest DKK3 concentrations were found in serum, followed by urine. Dialysate concentrations were significantly lower. Dialysate DKK3 correlated with both other compartments. Serum, dialysate and urine values were stable during three months of follow-up. Continuous ambulatory dialysis (CAPD) but not cycler-assisted peritoneal dialysis (CCPD) volume-dependently increased peritoneal DKK3 in relation to creatinine. RAAS blockade significantly decreased urinary, but not serum or peritoneal DKK3.

Our data provide a detailed characterization of DKK3 in peritoneal dialysis. They support the notion that the RAAS system is essential for renal DKK3 handling.