Abstract: FR-PO1104
Feasibility Study of Renal Functional Reserve Assessment Using an Oral Protein Bolus and Serial Creatinine Clearance Measurements
Session Information
- Health Maintenance, Nutrition, and Metabolism
November 07, 2025 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Health Maintenance, Nutrition, and Metabolism
- 1500 Health Maintenance, Nutrition, and Metabolism
Authors
- Piggott, Raymond Simon, University College Dublin Diabetes Complications Research Centre, Dublin, Leinster, Ireland
- Andrews, Darrell C., University College Dublin Diabetes Complications Research Centre, Dublin, Leinster, Ireland
- Holian, John, St Vincent's University Hospital, Dublin, Leinster, Ireland
- Murray, Patrick T., University College Dublin Diabetes Complications Research Centre, Dublin, Leinster, Ireland
- Le Roux, Carel W., University College Dublin Diabetes Complications Research Centre, Dublin, Leinster, Ireland
- Sadlier, Denise M., Mater Misericordiae University Hospital, Dublin, Leinster, Ireland
- Godson, Catherine, University College Dublin Diabetes Complications Research Centre, Dublin, Leinster, Ireland
- Docherty, Neil G., University College Dublin Diabetes Complications Research Centre, Dublin, Leinster, Ireland
Background
Renal functional reserve (RFR) reflects the kidney’s ability to augment glomerular filtration rate (GFR) in response to stress. While resting GFR shows baseline renal function, RFR captures subclinical nephron adaptability and may offer insight into early dysfunction not detected by standard measures. RFR is assessed by comparing baseline GFR with stress GFR after an oral protein load. In this protocol, GFR was estimated using creatinine clearance (CrCl), a practical method. This feasibility study aimed to evaluate the physiological responsiveness and reliability of an RFR protocol for future study in individuals with obesity.
Methods
Ten healthy adults (5 male, 5 female; mean age 31.5 ± 6.9 years) underwent RFR testing in a fasting state. On arrival, baseline assessments included weight, glucose, and bladder emptying, followed by venous cannulation. Hydration was standardized with ingestion of 10 mL/kg water over 10 minutes. Two 1-hour urine collections with venous blood samples determined baseline CrCl. Participants then ingested a 300 mL shake containing 100 g of commercially available whey isolate. Two more 1-hour urine collections with blood draws were done starting 1 hour post-ingestion to calculate stimulated CrCl. RFR was defined as the difference between stimulated and baseline CrCl.
Results
All participants completed the protocol. Mean baseline CrCl was 153.4 ± 49.8 mL/min. CrCl increased significantly to 248.6 ± 60.0 mL/min post protein bolus (p = 0.0002). Mean RFR was 95.2 ± 48.5 mL/min. Males had a baseline CrCl of 141 mL/min and RFR of 74.2 ± 39.1 mL/min, while females had baseline CrCl of 137 mL/min and RFR of 116 ± 51.6 mL/min.
Conclusion
This study demonstrated a consistent increase in CrCl following a standardized oral protein load, supporting the utility of the protocol as a means of RFR assessment. A fixed 100 g protein dose was selected to enhance tolerability and feasibility in individuals with BMI >30kg/m2, a weight-based load (e.g. 1 g/kg) may be excessive or clinically impractical.The reproducibility and operational reliability of this approach make it well-suited for longitudinal application in populations at risk for subclinical CKD, for example in persons living with obesity.