An observational study in Peritoneal Dialysis (PD), End Stage Renal Disease (ESRD) and Peritoneal Fibrosis, sponsored by Universität des Saarlandes. Not yet recruiting at 1 site in Germany. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-09-08.
Sponsored by Universität des Saarlandes · Observational
Peritoneal dialysis (PD) uses the peritoneal membrane as a natural filter to remove waste products from the blood in patients with kidney failure. Over time, the peritoneal membrane can become scarred and less functional - a process called peritoneal fibrosis - which eventually leads to ultrafiltration failure and loss of the PD technique. Currently, there is no reliable early biomarker to detect this process before it causes clinical problems.
PERIMARK is a prospective, single-center, observational study investigating whether DKK3 (Dickkopf-3), a protein involved in fibrosis signaling, can serve as an early biomarker of peritoneal membrane deterioration. DKK3 will be measured in urine, peritoneal dialysate and serum at four time points over 12 months (T0: catheter insertion; T1: 12 weeks; T2: 6 months; T3: 12 months). At each follow-up visit, peritoneal membrane function will be assessed by the Modified Peritoneal Equilibration Test (Modified PET) with 3.86% glucose, measuring the sodium dip (ΔDNa) as a marker of aquaporin-1-mediated water transport and D/P creatinine as a marker of small solute transport.
The primary endpoint is the intraindividual change in DKK3/creatinine ratio in urine, dialysate and serum from baseline to 12 months. Secondary endpoints include the correlation of DKK3 with the sodium dip, longitudinal changes in peritoneal transport parameters, and the exploratory question of whether an early DKK3 rise predicts a later decline in aquaporin-1 function.
The study also includes a biobank of serum, urine, dialysate supernatant and cell pellets for possible future analyses. Target enrollment is 25-30 patients.
Background: Peritoneal fibrosis is the main limiting factor for long-term peritoneal dialysis. The underlying mechanism is mesothelial-to-mesenchymal transition (MMT), driven by TGF-β1 and the Wnt/β-catenin pathway. DKK3 is a profibrotically active glycoprotein acting as an amplifier in this network. The only published study of DKK3 in PD dialysate (Ehleiter et al., BMC Nephrology 2024, n=29) demonstrated measurable DKK3 levels and called for longitudinal follow-up studies. No prospective 12-month longitudinal study exists.
Study Design: Prospective, monocentric, non-interventional, exploratory cohort study with biobanking. No randomization, no blinding, no intervention. All treatment decisions remain with the treating physician.
Time Points:
T0 (Day 0): PD catheter insertion. Baseline blood and urine sampling. Initial peritoneal lavage sample for dialysate DKK3 baseline.
T1 (12 weeks / \~90 days): First Modified PET. Blood, urine and dialysate sampling. Combined with catheter quality control assessment.
T2 (6 months): Second Modified PET. Blood, urine and dialysate sampling. T3 (12 months): Third Modified PET. Blood, urine and dialysate sampling. Primary endpoint time point.
T30 (30 days): Telephone interview for catheter complication assessment only.
Modified PET Method: Performed according to La Milia et al. (Kidney Int 2006; DOI: 10.1038/sj.ki.5000183) using 2L of 3.86% glucose solution. Key parameters: sodium dip (ΔDNa at 60 min, reference value 8.4 ± 3.8 mmol/L) as aquaporin-1 marker, D/P creatinine at 240 min for transporter classification, and net ultrafiltration by weighing.
Biobanking: Dialysate samples are centrifuged at 400×g, 4°C, 10 minutes. Supernatant is stored at -80°C for DKK3 ELISA and future biomarker analyses. Cell pellets are cryopreserved in CryoStor CS10 at -196°C for possible future single-nucleus RNA sequencing or proteomics. Serum and urine aliquots are stored at -80°C.
DKK3 Measurement: Human DKK3 ELISA ReFine (by DiaRen). Dialysate samples diluted 1:50 in kit sample buffer prior to measurement (validated by spike-recovery: \~102% at 1:50 dilution). Creatinine in dialysate measured by enzymatic method (Jaffé method excluded due to glucose interference validated internally). Sodium measured by indirect ISE (COBAS); no correction formula required as validated internally.
Statistical Analysis: Exploratory study, no confirmatory hypothesis testing. Wilcoxon signed-rank test for paired comparisons, Spearman correlation for association analyses. No correction for multiple testing. Separate analysis of intention-to-treat and per-protocol populations. Urinary DKK3 evaluated only in patients with residual renal function >0 ml/24h.
2,108 studies on the registry are indexed under Kidney Failure, Chronic; 273 are open to participants now.
This study's planned enrollment of 30 is below the median of 120 across 442 observational studies indexed under Kidney Failure, Chronic.
Browse Kidney Failure, Chronic studies →Universität des Saarlandes is the lead sponsor of 68 studies on the registry; 17 are open to participants now.
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Consecutive adult patients with end-stage renal disease undergoing PD catheter insertion at the Department of Internal Medicine IV, Saarland University Medical Center, Homburg, Germany.
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Exclusion Criteria:
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Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
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The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Life expectancy
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Consecutive adult patients with end-stage renal disease starting peritoneal dialysis after PD catheter insertion at the Department of Internal Medicine IV, Saarland University Medical Center. No comparator group.
Diagnostic Test: Modified Peritoneal Equilibration Test and DKK3 Biomarker Measurement
Modified Peritoneal Equilibration Test (Modified PET) performed with 2L of 3.86% glucose solution according to La Milia et al. (Kidney Int 2006; DOI: 10.1038/sj.ki.5000183). Parameters assessed: sodium dip (ΔDNa at 60 min) as aquaporin-1 marker, D/P creatinine at 240 min for transporter classification, and net ultrafiltration by weighing. Concurrent blood, urine and peritoneal dialysate sampling for DKK3 measurement (Human DKK3 DuoSet ELISA, R\&D Systems) and biobanking. No drug or therapeutic agent is administered.
Also known as: Modified PET, mPET
Change in DKK3/Creatinine Ratio in Urine, Dialysate and Serum
Intraindividual change in DKK3/creatinine ratio in urine, peritoneal dialysate and serum from baseline (T0) to 12 months (T3). Measured by DKK3 ReFine ELISA (DiaRen).
Time frame: 12 months
Change in D/P Creatinine
Longitudinal change in dialysate-to-plasma creatinine ratio (D/P creatinine) at 240 minutes in Modified PET from T1 to T3.
Time frame: 12 weeks to 12 months
Correlation of DKK3 with Sodium Dip (ΔDNa)
Spearman correlation between DKK3/creatinine ratio in dialysate and sodium dip (ΔDNa) in Modified PET at T1, T2 and T3.
Time frame: 12 weeks, 6 months, 12 months
Net Ultrafiltration and Ultrafiltration Failure
Net ultrafiltration (ml) after 4-hour dwell with 3.86% glucose solution. Incidence of ultrafiltration failure defined as net UF \<400 ml.
Time frame: 12 weeks, 6 months, 12 months
Change in Residual Renal Function
Change in 24-hour urine volume and eGFR (CKD-EPI) from baseline to 12 months.
Time frame: 12 months
Peritoneal Transporter Classification
Classification of peritoneal transport type (Low, Low-Average, High-Average, High) based on D/P creatinine at 240 minutes according to La Milia 2006.
Time frame: 12 weeks, 6 months, 12 months
Early DKK3 Rise as Predictor of Later Aquaporin-1 Decline
Exploratory linear regression analysis: association between early DKK3 change (T0 to T1) and subsequent decline in sodium dip ΔDNa (T1 to T2).
Time frame: 12 weeks to 6 months
Plan to share: No — No plan to share individual participant data. Aggregated, anonymized study results will be published in a peer-reviewed journal upon study completion.
Start is estimated for Sep 2026; primary completion for Dec 2028, 27 months later.
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Universität des Saarlandes