About the eGFR Calculator
This calculator uses the 2021 CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) creatinine equation, the current standard for estimating glomerular filtration rate in adults. The 2021 version was updated to remove the race variable, addressing concerns about race-based adjustments in clinical practice.
CKD-EPI 2021 Formula
eGFR = 142 × min(Scr/κ, 1)α × max(Scr/κ, 1)−1.200 × 0.9938Age × (1.012 if Female)
Where κ = 0.7 (female) or 0.9 (male), α = −0.241 (female) or −0.302 (male).
CKD Stage Classification (KDIGO 2022)
| Stage | eGFR (mL/min/1.73m²) | Description | Action |
|---|---|---|---|
| G1 | ≥ 90 | Normal or high | Treat underlying cause |
| G2 | 60–89 | Mildly decreased | Evaluate for CKD progression |
| G3a | 45–59 | Mildly-moderately decreased | Monitor q6–12 months |
| G3b | 30–44 | Moderately-severely decreased | Nephrology co-management |
| G4 | 15–29 | Severely decreased | Prepare for renal replacement |
| G5 | < 15 | Kidney failure | Dialysis or transplant evaluation |
When to Use eGFR
eGFR should be used to: stage chronic kidney disease, guide medication dosing (especially renally-cleared drugs), determine need for contrast agent premedication, and monitor progression of renal disease. eGFR is part of the full CKD assessment — albuminuria (uACR) should also be assessed to complete risk stratification.
Limitations
The CKD-EPI equation is less accurate in patients with extremes of body composition, amputees, vegetarian diets, or acute kidney injury. For AKI or rapidly changing renal function, serial creatinine trends are more informative than a single eGFR estimate. Consider cystatin C-based eGFR when creatinine-based estimates are unreliable.
References
Inker LA, et al. New Creatinine- and Cystatin C–Based Equations to Estimate GFR without Race. N Engl J Med. 2021;385:1737–1749.
KDIGO 2022 CKD Guideline. Kidney Int Suppl. 2022;104(4S):S117–S314.