A Methodological Study to Learn More About Kidney Function in Healthy People and in People With Reduced Kidney Function

Study to Investigate Renal Functional Reserve in Healthy Participants and in Participants With Impaired Renal Function.

The main purpose of this study is to investigate how reliable a test assessing the renal functional reserve (RFR) and the maximum glomerular filtration rate (maxGFR) are. MaxGFR and RFR assessments are repeated twice at 1-month intervals. If precise, this test may improve the measure of kidney function and be useful in future studies for people with chronic kidney problems.

To do this, the researchers will collect and analyze information about kidney function from up to 50 adults, including healthy people and people with stable kidney problems. Each person will come to the study center for a screening visit and then three study days, each about a month apart. On each study day, participants will have blood and urine samples taken before and after drinking a protein shake. The tests will measure things like creatinine, cystatin C, and other markers in the blood and urine to see how the kidneys are working. The study will also record basic health information, weight, blood pressure, and any medicines being taken.

The study will last about 2 to 2.5 months for each participant.

Study Overview

• Status: Recruiting
• Conditions: Acute Kidney Injury, Renal Insufficiency
• Intervention / Treatment: Other: No investigational study intervention

• Study Type: Interventional
• Enrollment (Estimated): 50
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Bayer Clinical Trials Contact; Phone Number: (+)1-888-84 22937; Email: clinical-trials-contact@bayer.com

Study Locations

• Germany
  • Berlin, Germany, 13353
    • Recruiting
    • Bayer AG - Occupational Health Services

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Participant must be 18 to 75 years of age inclusive, at the time of signing the ICF.
• Stable medical condition defined as no new drug or other treatment prescribed for a chronic condition within 60 days prior to Study Day 1.
• Body weight between 50 and 100 kg.
• Female Participants: A participant is eligible to participate if not pregnant or breastfeeding. If a urine test cannot be confirmed as negative at screening (e.g., an ambiguous result), the participant must be excluded from participation.

Exclusion Criteria:

• Recent surgical intervention within 60 days prior to Study Day 1.
• New clinical diagnosis established within 60 days prior to Study Day 1.
• New drug prescription within 60 days prior to Study Day 1.
• Relevant change in severity of any medical condition within 60 days prior to Study Day 1, e.g. disease flare.
• Known congenital amino acid metabolism disorders.
• Severe hypersensitivity to milk products.
• Known liver cirrhosis.
• Regular use of non-steroidal anti-inflammatory drugs (NSAIDs).
• Impaired kidney function with eGFR <30 mL/min/1.73m2

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Diagnostic
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Other: Group 1	Other: No investigational study intervention; The study does not involve the administration of any study intervention, investigational medicinal product, or device. Participants will undergo blood collection and urine sampling both before and after consuming a high-protein meal.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Maximun kidneyfunction determined by measurement of creatinine clearance (mGFRCR)	Day 1, 28 and 56
Renal functional reserve by measurement of creatinine clearance (mGFRCR)	Day 1, 28 and 56

Secondary Outcome Measures

Outcome Measure	Time Frame
Maximum kidney function and renal functional reserve derived from serum creatinine-based eGFR (eGFRSCR)	Day 1, 28 and 56
Maximum kidney function and renal functional reserve derived from serum cystatin C-based eGFR (eGFRCYS)	Day 1, 28 and 56
Maximum kidney function and renal functional reserve derived from serum creatinine-based and serum cystatin C-based eGFR (eGFRSCR-CYS)	Day 1, 28 and 56
Maximum creatinine clearance and renal functional reserve derived from plasma PENK-based eGFR (eGFRPENK)	Day 1, 28 and 56

Collaborators and Investigators

• Sponsor: Bayer

Study record dates

Study Major Dates

• Study Start (Actual): January 6, 2026
• Primary Completion (Estimated): February 19, 2027
• Study Completion (Estimated): February 19, 2027

Study Registration Dates

• First Submitted: January 2, 2026
• First Submitted That Met QC Criteria: January 23, 2026
• First Posted (Actual): January 27, 2026

Study Record Updates

• Last Update Posted (Actual): July 6, 2026
• Last Update Submitted That Met QC Criteria: July 2, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Urogenital Diseases; Male Urogenital Diseases; Kidney Diseases; Urologic Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Acute Kidney Injury; Renal Insufficiency
• Other Study ID Numbers: 23125

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Currently, there is no established plan for the sharing of Individual Patient Data (IPD) from this study. The availability of this study's data will later be determined according to Bayer's commitment to the EFPIA/PhRMA 'Principles for responsible clinical trial data sharing.' This pertains to the scope, timepoint, and process of data access. As such, Bayer commits to considering requests from qualified researchers for patient- / study-level clinical trial data, and documents from clinical trials involving medicines and indications approved in the US and EU. However, this commitment does not reflect an active IPD sharing plan. This applies to data on new medicines and indications that have been approved by the EU and US regulatory agencies on or after January 01, 2014. Researchers can use www.vivli.org to request access to IPD and documents from clinical studies to conduct research. Information on Bayer's criteria for listing studies is provided in the member section of the portal.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No