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Estimated GFR: time for a critical appraisal
Esteban Porrini1,2, Piero Ruggenenti3,4, Sergio Luis-Lima5,6
1Hospital Universitario de Canarias, Tenerife, Spain. esteban.l.porrini@gmail.com.
Nature Reviews. Nephrology
|December 7, 2018
Summary
Estimated glomerular filtration rate (eGFR) equations often misdiagnose chronic kidney disease (CKD). Over 70 equations using creatinine or cystatin C show significant errors, questioning their reliability for assessing renal function.
Area of Science:
- Nephrology
- Biomarkers
- Clinical Chemistry
Background:
- Over 70 equations estimating glomerular filtration rate (GFR) using creatinine and/or cystatin C have been developed since 1957.
- The accuracy of these estimated GFR (eGFR) equations in reflecting true renal function remains a subject of debate.
Purpose of the Study:
- To evaluate the accuracy of current eGFR equations by comparing them with measured GFR (mGFR).
- To identify the extent and nature of discrepancies between eGFR and mGFR across diverse patient populations.
Main Methods:
- Analysis of over 70 studies comparing eGFR and mGFR.
- Inclusion of approximately 40,000 patients with chronic kidney disease (CKD), type 2 diabetes mellitus, polycystic kidney disease, and renal transplant recipients.
Main Results:
- eGFR frequently deviated from mGFR by ±30% or more.
- eGFR inaccurately staged CKD in 30-60% of patients.
- Discrepancies were observed in rates of GFR decline between eGFR and mGFR, with unpredictable and comparable errors for both creatinine- and cystatin C-based equations.
Conclusions:
- The persistent inaccuracies suggest that creatinine and cystatin C are inherently limited as markers for renal function.
- The issue likely stems from the choice of biomarkers rather than the mathematical estimation methods.
- Rethinking the fundamental markers used for GFR assessment is warranted.
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