How eGFR (CKD-EPI 2021) is calculated
Estimated glomerular filtration rate uses serum creatinine, age, and sex in the 2021 CKD-EPI creatinine equation — the current race-free reference standard.
Result is reported in mL/min/1.73m², i.e. normalised to a standard body surface area.
Normal values & CKD staging
| Stage | eGFR (mL/min/1.73m²) | Description |
|---|---|---|
| G1 | ≥ 90 | Normal or high (needs other marker of kidney damage to call CKD) |
| G2 | 60 – 89 | Mildly decreased |
| G3a | 45 – 59 | Mild–moderate CKD |
| G3b | 30 – 44 | Moderate–severe CKD |
| G4 | 15 – 29 | Severe CKD |
| G5 | < 15 | Kidney failure |
Clinical use
eGFR is the standard tool for staging chronic kidney disease (combined with albuminuria/ACR in the KDIGO "heat-map" grid), monitoring progression, and triggering nephrology referral (typically at G4/G5, rapid decline, or uncontrolled complications). It's less reliable at extremes of muscle mass, in acute kidney injury (creatinine hasn't reached steady state), pregnancy, or amputees — in those settings cystatin C-based or measured clearance is preferred.
Frequently asked questions
What is eGFR?
Estimated glomerular filtration rate (eGFR) is a calculated measure of kidney function derived from serum creatinine, age, and sex — used to stage chronic kidney disease and monitor kidney health over time.
What is a normal eGFR?
90 mL/min/1.73m² or higher is considered normal or high (Stage G1); a diagnosis of CKD at this level still requires another marker of kidney damage, such as proteinuria.
What does a low eGFR mean?
A lower eGFR indicates reduced kidney filtering capacity — values below 60 sustained over 3+ months indicate chronic kidney disease, with severity graded G2 through G5 as eGFR falls further.
Why doesn't the CKD-EPI 2021 equation use race anymore?
The updated 2021 CKD-EPI equation removed the race coefficient used in earlier versions after evidence showed race-based adjustment could systematically over-estimate kidney function in Black patients, potentially delaying appropriate care.
Can eGFR fluctuate day to day?
Yes — hydration status, recent high protein intake, exercise, and muscle mass changes can all shift creatinine and therefore eGFR. A single abnormal reading is usually confirmed with a repeat test before diagnosing CKD.
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 2012 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int Suppl. 2013;3:1–150.