Kidney Week

Abstract: TH-PO1190

Creatinine-Based eGFR Equations Compared with Iothalamate-Measured GFR in Children and Young Adults

Session Information

• Pediatric Nephrology: CV Health, CKD, AKI, Dialysis, Transplantation, and Health Services Research
  October 22, 2026 | Location: Exhibit Hall A, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Pediatric Nephrology

• 1800 Pediatric Nephrology

Authors

• Benning, Tyler, Mayo Clinic Minnesota, Rochester, Minnesota, United States

Tyler Benning, MD, MS

• Sas, David J., Mayo Clinic Minnesota, Rochester, Minnesota, United States

David J. Sas, DO, MPH

• Tran, Cheryl L., Mayo Clinic Minnesota, Rochester, Minnesota, United States

Cheryl L. Tran, MD

• Cramer, Carl H., Mayo Clinic Minnesota, Rochester, Minnesota, United States

Carl H. Cramer, MD

• Larson, Timothy S., Mayo Clinic Minnesota, Rochester, Minnesota, United States

Timothy S. Larson, MD

• Rule, Andrew D., Mayo Clinic Minnesota, Rochester, Minnesota, United States

Andrew D. Rule, MD, MS, FASN

• Titan, Silvia, Mayo Clinic Minnesota, Rochester, Minnesota, United States

Silvia Titan, MD, PhD, FASN

• Hanna, Christian, Mayo Clinic Minnesota, Rochester, Minnesota, United States

Christian Hanna, MD, MS, FASN

Background

Accurate estimation of glomerular filtration rate (GFR) is essential for CKD staging and clinical decision-making. Pediatric patients (pts) require age-appropriate equations, yet transition to adult formulas introduces discontinuity and potential inaccuracy. We evaluated the performance of four creatinine-based estimated GFR (eGFR) equations across a broad age spectrum in an outpatient cohort.

Methods

We conducted a retrospective study of pts aged 2-25 years (y) who underwent measured GFR (mGFR) by iothalamate clearance at a single center. eGFR was calculated using the 2009 revised Schwartz, CKiD U25cr, EKFCcr, and CKD-EPIcr equations, applied within validated age ranges. Bias (mGFR-eGFR), accuracy (1-P30), and root mean square error (RMSE) were assessed, with analyses stratified by age and eGFR categories.

Results

The cohort included 1,685 pts (mean mGFR 91.5 mL/min/1.73 m²), with high clinical complexity, including transplant recipients (37%). All equations demonstrated modest performance with overlapping confidence intervals. Accuracy was lowest in younger children, particularly ages 2-5y, where >30% deviation from mGFR was common (Fig 1). Precision was higher in older pts and those with lower mGFR. Underestimation of mGFR increased at higher eGFR levels, except for the CKD-EPIcr equation which was prone to overestimation. Within age groups, differences in the accuracy between equations was modest.

Conclusion

Creatinine-based eGFR equations demonstrate limited accuracy in our cohort with 17-30% of pts showing errors larger than 30%. Accuracy was worse in ages 2-5y. No equation was consistently superior to others overall and across age groups. These findings highlight ongoing limitations of creatinine-based estimation and support careful interpretation of eGFR, particularly in younger pts and in those with preserved kidney function.