Abstract: FR-OR008
Cystatin C Reveals Sex Differences in Misclassified Kidney Recovery and Undetected CKD Among AKI Survivors in ASSESS-AKI
Session Information
- AKI Everywhere All at Once: Risks, Trajectories, and Practice Patterns
November 07, 2025 | Location: Room 320A, Convention Center
Abstract Time: 05:40 PM - 05:50 PM
Category: Acute Kidney Injury
- 101 AKI: Epidemiology, Risk Factors, and Prevention
Authors
- Birkelo, Bethany, University of Minnesota Twin Cities, Minneapolis, Minnesota, United States
- Siew, Edward D., Vanderbilt University, Nashville, Tennessee, United States
- Drawz, Paul E., University of Minnesota Twin Cities, Minneapolis, Minnesota, United States
Background
Acute kidney injury (AKI) and muscle loss are both common in hospitalized patients. AKI recovery is defined by decreases in serum creatinine to pre-hospital baseline. Muscle loss can reduce creatinine levels independent of changes in kidney function, complicating the assessment of kidney recovery after AKI. These factors are particularly relevant in females, as data shows muscle loss occurs more rapidly in females than males. Cystatin C is a non-muscle-based biomarker of kidney function.
Methods
We compared differences in estimated glomerular filtration rate (eGFR-diff) between creatinine and cystatin C measured in male and female AKI survivors three months after hospital discharge in the Assessment, Serial Evaluation, and Subsequent Sequelae in Acute Kidney Injury (ASSESS-AKI) study (N=772, 33% female). eGFR was calculated using the 2009 CKD-EPI equations. eGFR-diff was defined by subtracting cystatin C-based eGFR (eGFR-Cys) from creatinine-based eGFR (eGFR-Cr). We identified the proportions of both sexes in whom eGFR-Cys was >10 ml/min lower or >15 ml/min lower than eGFR-Cr. We determined the proportions of both sexes with eGFR-Cys 45–60 ml/min/1.73m2 or 15–44 ml/min/1.73m2 among patients with eGFR-Cr of ≥60 ml/min/1.73m2. We identified patients who recovered from AKI (defined by eGFR-Cr within 10% of baseline eGFR); among those, we identified the proportions of both sexes whose eGFR-Cys was not within 10% of baseline.
Results
The mean eGFR-diff was 15.5 ml/min in males and 19.2 ml/min in females (p=0.0045). Higher proportions of females had eGFR-Cr >10 ml/min and >15 ml/min higher than eGFR-Cys. eGFR-Cys indicated misclassified kidney recovery in 76% of females and 66% of males (P=0.03).
Conclusion
Female AKI survivors had Cys-Cr eGFR differences that were greater in magnitude and more commonly indicated potentially misclassified kidney recovery and undetected CKD compared to males.