---
title: The Practicality and Utility of Measured vs Estimated GFR in adCKD
nct_id: NCT07450534
overall_status: NOT_YET_RECRUITING
sponsor: Manchester University NHS Foundation Trust
study_type: OBSERVATIONAL
primary_condition: Chronic Kidney Disease (Stages 4 and 5)
countries: United Kingdom
canonical_url: "https://parkinsonspathways.com/agent/trials/NCT07450534.md"
clinicaltrials_gov: "https://clinicaltrials.gov/study/NCT07450534"
ct_last_update_post_date: 2026-03-04
last_seen_at: "2026-05-12T06:35:36.285Z"
source: ClinicalTrials.gov (mirrored, no enrichment)
---
# The Practicality and Utility of Measured vs Estimated GFR in adCKD

**Official Title:** The Practicality & Utility of Estimated vs Measured Renal Function in Advanced Kidney Disease, Whether Treated With Dialysis or Not: Can Better Techniques be Used to Predict the Onset of the Uraemic Syndrome and Guide Dialysis Requirements

**NCT ID:** [NCT07450534](https://clinicaltrials.gov/study/NCT07450534)

## Key Facts

- **Status:** NOT_YET_RECRUITING
- **Study Type:** OBSERVATIONAL
- **Target Enrollment:** 150
- **Lead Sponsor:** Manchester University NHS Foundation Trust
- **Conditions:** Chronic Kidney Disease (Stages 4 and 5), Chronic Kidney Disease 5D
- **Start Date:** 2026-02
- **Completion Date:** 2027-02
- **CT.gov Last Update:** 2026-03-04

## Brief Summary

The goal of this observational study is to assess if new ways of measuring kidney function can better predict when individuals will become symptomatic due to kidney failure, and whether residual kidney function can be accurately measured in those already on dialysis.

The main questions the study is trying to answer is whether measuring kidney function by clearance of iohexol is comparable to the current standard of care methods.

In addition to routine care, participants will:

* undergo a brief clinical assessment
* be given an injection of iohexol and asked to perform 4 finger prick blood tests over 24 hours, recording the time of each sample. Samples will be returned in person or posted back
* be asked to complete a questionnaire on their experience

## Detailed Description

The eligible study population includes all adults under the care of nephrology at Manchester Foundation Trust with advanced chronic kidney disease approaching end stage renal failure and those established on haemodialysis who still produce urine. This pilot study aims to collect 50 measurements in each of three groups of participants (total 150): (1) those with advanced kidney disease not yet on dialysis; (2) those undergoing peritoneal dialysis and (3) those undergoing haemodialysis who still have residual kidney function. Those who have not yet started dialysis will have repeat measurements when they become symptomatic with renal failure and a third time after they are established on dialysis (either peritoneal or haemo-) to assess for a threshold of renal function at which individuals need to start dialysis, and consistency of the measurements whether undergoing dialysis or not. This will mean a maximum of 150 participants would be required.

Screening and recruitment will take place in advanced kidney care clinics, peritoneal dialysis clinics and dialysis units managed by Manchester University NHS Foundation Trust. Potential participants will be given information about the study by their usual care provided and, if agreeable, contacted later by the research team for further discussion and formal recruitment to the study.

Study methods:

======== Participants will have up to three sets of tests taken as part of the study depending at what stage they are recruited.

Each set of tests is done over one planned visit to hospital, except for those on haemodialysis where samples are taken from two consecutive visits. All study visits coincide with routine care with no study specific hospital visits.

For those not yet started on dialysis, at the participant's next kidney clinic they will have a brief assessment by the research team and confirmation of their medical background. They will be given a demonstration and provided with information about how to perform finger prick tests at home. Instead of having their usual bloods taken for clinic, a small cannula will be inserted and bloods for the study will be taken at the same time as any bloods requested by their doctor. 5ml of iohexol will be injected and the cannula removed. This should take approximately 15 minutes in total. They will be asked to stay on site for 30 minutes for observation. Urine samples collection is required for analysis although this is part of routine care. Participants will be provided with equipment and asked to take 4 finger prick blood samples at home over the next 24 hours. These should be as close as possible to 3, 6, 10 and 24 hours after the injection but will be flexible to fit around lifestyle and planned times for samples agreed with the participant. The research team will contact them within an hour before the first and last sample as a reminder. These samples can be posted back in a prepaid and addressed envelope at the participant's convenience.

Participants will also be given a brief questionnaire to complete about the experience and return along with the finger prick samples.

Participants will be followed up remotely at each subsequent clinic visit. Once their medical team identifies them as needing to start dialysis, participants will be approached again by the research team (either at the same or their subsequent clinic visit). The same process will be applied for brief clinical assessment, blood \& urine sampling, injection of iohexol, finger prick technique demonstration and finger prick sampling. Participants will not be given a second questionnaire. Participants may be waiting to start dialysis at the time of recruitment to the study - in this circumstance they will not have this second set of study tests prior to starting dialysis.

Participants will continue to be followed up remotely and once established on dialysis for at least a week will be approached for a third time by the research team at one of their dialysis visits.

In those who are undergoing peritoneal dialysis, the next study visit will coincide with their next clinic where 24-hour urine collection is planned (done as routine care). The process for assessment and sample collection will be be the same as in the predialysis setting. The results from the 24 hour urine collection are of interest to the study but are not study specific. Participants already on peritoneal dialysis can be directly recruited at this stage. Participants will be given a questionnaire only if they have not already completed one. Participants will have completed their time in the study after this.

In those established on haemodialsyis, the next study visit will coincide with the next dialysis visit where interdialytic urinary collection is planned (done as routine care). Participants will undergo a brief clinical assessment given a demonstration of finger prick sampling and asked to provide a urine sample as in the predialsyis setting. Blood samples for study purposes will be taken at the start of their dialysis session from their usual dialysis access at the same time as routine bloods. Additional blood samples will be taken at the end of dialysis as part of routine care. 5ml iohexol will be injected via their usual dialysis access after the dialysis session is completed but before they are disconnected. They will then be disconnected as per usual care but asked to remain on site for 30 minutes. As above, participants will be asked to collect 4 finger prick blood samples over the following 24 hours. These samples will be brought back to their next dialysis session. Further blood samples will be taken at the start and end of the subsequent dialysis session from their usual dialysis access at the same time as routine bloods. Participants already on haemodialsyis can be recruited to the study directly at this stage. Participants will be given a questionnaire only if they have not already completed one. Participants will have completed their time in the study after this.

Rationale for methodology:

The study design has been chosen in this way to minimise impact on the participant. Study visits will coincide with planned hospital visits to minimise any additional time and travel burden. Blood tests specific for the study will all be done simultaneously with routine blood sampling. No additional venepuncture is therefore required. For those on dialsyis, study visits will coincide specifically with visits where urine collection is planned as routine. This will avoid the need for additional samples and associated burden to participants.

The design is also chosen to coincide with routine hospital visits in this way to emulate how the test might be done in routine clinical care.

Convenience sampling for participant recruitment will be used. In the predialysis and peritoneal dialysis cohort, recruitment through clinic only will allow all interactions and blood sampling to coincide with planned hospital visits. In the dialysis cohort, recruitment will be clustered by dialysis unit initially recruiting from those units that send their routine blood samples to Manchester Royal Infirmary's laboratories, then according to unit size. By doing this participants can be tested simultaneously and sample handling costs minimised. The specific dialysis unit that a patient attends is based on geographical proximity to their home. The investigators expect very little clinical variation between different units and would not expect this methodology to impact results.

## Eligibility

- **Minimum age:** 18 Years
- **Sex:** ALL
- **Healthy Volunteers:** No

```
Inclusion Criteria:

* Adults (18 year s or older)
* Able to give informed consent
* Progressive chronic kidney disease predicted to start renal replacement therapy in the next 6 months OR established on dialysis (either haemodialysis or peritoneal) with residual renal function (Urine output \>100ml/day)

Exclusion Criteria:

* Under 18 years
* Known allergy to iodinated contrast media
* Unable to perform fingerprick blood testing
* Unable to comply with urine collection
* Unable or unwilling to give informed consent in English
* Acute kidney injury expected to recover renal function
* Pre-dialysis and planned renal transplant within 1 month
* Pregnant or breast feeding
* Significant fluid overload (significant peripheral oedema or ascites AND \>10kg above estimated dry weight)
```

## Arms

- **Advanced Chronic Kindney Disease expected to need dialysis in the next 6 months** — As per study description: individuals with progressive advanced chronic kidney disease. Interventions of interest include iohexol injection and 4x finger prick sample collection; clinical review; questionnaire. Routine blood and urine tests are also of interest.
- **End stage kidney disease established on peritoneal dialysis with >100ml / 24hours urine output** — As per study description: individuals with established end stage chronic kidney disease undergoing peritoneal dialysis. Interventions of interest include iohexol injection and 4x finger prick sample collection; clinical review; questionnaire. Routine blood, urine and peritoneal fluid tests are also of interest.
- **End stage kidney disease established on haemodialysis with >100ml / 24hour urine output** — As per study description: individuals with established end stage chronic kidney disease undergoing haemodialysis. Interventions of interest include iohexol injection and 4x finger prick sample collection; clinical review; questionnaire. Routine blood and urine tests are also of interest.

## Interventions

- **Iohexol Inj 300 MG/ML Diagnostic aid/agent used to measure glomerular filtration rate (GFR)** (DIAGNOSTIC_TEST) — Injection of 3235mg iohexol (equivalent to 5ml Omnipaque 300) followed by serial dried blood spot testing over 24 hours to be measured for iohexol concentration and used to calculate clearance.

## Primary Outcomes

- **Iohexol measured glomerular filtration rate** _(time frame: Assessed at each study visit through study completion, up to 6 months.)_ — Serial timed dried blood samples taken over 24 hours after injection of iohexol will be tested for iohexol concentration. The measured glomerular filtration rate will be calculated by the rate of clearance (the area under the curve for concentration vs time plot) and corrected for body surface area (derived by weight and height) to give a value in ml/min/1.73m\^2
- **Creatinine based estimated glomerular filtration rate (Standard of care measure for kidney function in those not receiving renal replacement therapy)** _(time frame: Assessed at each study visit while the participant has not yet started renal replacement therapy through study completion, up to 6 months.)_ — Serum creatinine concentration (micromoles/liter) will be measured from a venous blood sample. This concentration along with participant age and sex will be used to calculate estimated glomerular filtration rate, corrected for body surface area, from internationally validated mathematical equations. Resuilts are reported in ml/min/1.73m\^2
- **Creatinine clearance corrected for body surface area (Standard of care measure for kidney function in those receiving peritoneal dialysis)** _(time frame: Assessed at any study visit where the participant is established on peritoneal dialysis through to study completion, usually 48 hours after this visit.)_ — Creatinine clearance will be calculated from paired blood (serum creatinine concentration) and 24 hour urine (urine creatinine concentration and volume) using validated mathematical equations. This will be corrected for body surface area (derived by weight and height) to give a value in ml/min/1.73m\^2
- **Residual renal clearance of creatinine and urea (Standard of care measure for kidney function in those receiving haemodialysis)** _(time frame: Assessed at any study visit where the participant is established on haemodialysis dialysis through to study completion, usually 48 hours after this visit.)_ — Renal function in haemodialysis can be derived from averaging the measured creatinine and urea clearance. This is calculated using internationally validated equations and requires multiple measurements. This includes: Pre- and post- dialyisis serum creatinine \& urea concentrations from 1st dialysis visit; timed urine collection between dialysis periods measured for urine creatinine and urea concentration, volume, time of collection and time between end of dialysis visit and starting urine collection; And predialsyis serum creatinine and urea from subsequent (2nd) dialysis session.

This will be corrected for body surface area (derived by weight and height) to give a value in ml/min/1.73m\^2

## Secondary Outcomes

- **Patient acceptability of performing measured GFR as assessed by participant questionnaire** _(time frame: 24 hours. The questionnaire should take no more than 5 minutes but requires completion of the participant's first 24 hour mGFR testing to be done.)_
- **Number of iohexol finger prick samples correctly returned** _(time frame: Assessed at each study visit through study completion, up to 6 months.)_
- **Single sample iohexol measured GFR** _(time frame: Assessed at each study visit through study completion, up to 6 months.)_
- **eGFR calculated by novel markers** _(time frame: Assessed at each study visit through study completion, up to 6 months.)_
- **Presence of uraemic syndrome** _(time frame: Assessed at each study visit through study completion, up to 6 months.)_
- **Concentrations of markers of renal tubular function** _(time frame: Assessed at each study visit through study completion, up to 6 months.)_

## Locations (1)

- Manchester Royal infirmary, Manchester, United Kingdom

## Recent Field Changes (last 30 days)

- `status.overallStatus` — added _(2026-05-12)_
- `status.primaryCompletionDate` — added _(2026-05-12)_
- `status.completionDate` — added _(2026-05-12)_
- `status.lastUpdatePostDate` — added _(2026-05-12)_
- `design.enrollmentCount` — added _(2026-05-12)_
- `eligibility.criteria` — added _(2026-05-12)_
- `eligibility.minAge` — added _(2026-05-12)_
- `eligibility.sex` — added _(2026-05-12)_
- `outcomes.primary` — added _(2026-05-12)_
- `outcomes.secondary` — added _(2026-05-12)_
- `armsInterventions.arms` — added _(2026-05-12)_
- `armsInterventions.interventions` — added _(2026-05-12)_
- `sponsor.lead` — added _(2026-05-12)_
- `results.hasResults` — added _(2026-05-12)_
- `locations.manchester royal infirmary|manchester||united kingdom` — added _(2026-05-12)_

---

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