Abstract: FR-PO0730
Creatinine (Cr), Cystatin C (Cys), or Both? Real-Life Implications of Pediatric eGFR Equations in a Mexican Nephrology Cohort
Session Information
- Pediatric Nephrology: CKD, ESKD, and Glomerular Diseases
November 07, 2025 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Pediatric Nephrology
- 1900 Pediatric Nephrology
Authors
- Morales-Montes, Edgar Eduardo, Hospital Infantil de Mexico Federico Gomez, Mexico City, CDMX, Mexico
- Vargas-Torrico, Tamara, Hospital Infantil de Mexico Federico Gomez, Mexico City, CDMX, Mexico
- Valverde, Saul, Hospital Infantil de Mexico Federico Gomez, Mexico City, CDMX, Mexico
- Castañeda, Maria Cristina, Hospital Infantil de Mexico Federico Gomez, Mexico City, CDMX, Mexico
Background
Estimating glomerular filtration rate (eGFR) in pediatrics is challenging. While Schwartz and Zappitelli are widely used, newer dual-marker formulas like CKiD-U25 may offer better accuracy. We assessed the impact of switching formulas in real-world pediatric nephrology.
Methods
We analyzed 381 outpatients (ages 2–18) from a Mexican tertiary nephrology center (Jan–Apr 2025), including new and follow-up visits. We compared Schwartz (Cr, Cys), Zappitelli, CKiD-U25 (Cr, Cys, Cr/Cys), and CKD-EPI (≥16y) using Friedman/Wilcoxon, Spearman, Bland–Altman, and KDIGO staging (G0–G3/5), with chi-squared and Kappa.
Results
Schwartz-Cr overestimated eGFR vs Zappitelli/Schwartz-Cys (bias +34.4, LOA −31.7 to +100.6; ρ = 0.62), with significant difference (Wilcoxon p < 0.0001). CKD-EPI was excluded due to persistent overestimation.
CKiD-U25 Cr/Cys gave intermediate values, reducing the over- and underestimation seen with Schwartz and Zappitelli. It showed stronger correlations (ρ = 0.90 vs Schwartz; ρ = 0.78 vs Zappitelli) and a more balanced bias profile, bridging the gap between Cr and Cys formulas.
Staging varied notably: Schwartz vs Zappitelli showed poor agreement (Kappa = 0.091), and 31% were reclassified using CKiD Cr/Cys. The dual-marker formula outperformed single-marker disagreement and showed a stable age-related trend.
Conclusion
Creatinine and cystatin based formulas differ notably; the CKiD-U25 Cr/Cys equation offers a consistent, balanced alternative. Strengths: national referral base. Limitations: no gold-standard (mGFR).