Nephrology
eGFR (CKD-EPI 2021)
Estimated GFR, race-free creatinine equation.
Education and reference only. Not a substitute for clinical judgement, local policy or product labelling. Always verify before clinical use. Values are calculated in your browser and never stored.
Background
This estimates the glomerular filtration rate (eGFR) — a measure of kidney function — from serum creatinine using the 2021 CKD-EPI creatinine equation, together with age and sex. The 2021 equation notably removed the previous race coefficient. The result is reported in mL/min/1.73 m², i.e. indexed to an average adult body surface area, and is used to stage chronic kidney disease (CKD) and to monitor kidney function over time.
Interpreting the result
eGFR is used with the CKD G-stages: G1 is ≥90 (normal or high), G2 is 60–89 (mildly reduced), G3a is 45–59 and G3b is 30–44 (mild-to-moderate and moderate-to-severe), G4 is 15–29 (severely reduced) and G5 is <15 (kidney failure). Importantly, an eGFR of 60–89 is only CKD if there is also a marker of kidney damage (such as albuminuria); and a reduced value must be sustained for more than three months to indicate chronic, rather than acute, disease.
Worked example
A 65-year-old man with a serum creatinine of 130 µmol/L has an eGFR of roughly 50 mL/min/1.73 m², which is CKD stage G3a. If this is confirmed on repeat testing more than three months apart (and other causes excluded), it represents stage 3a chronic kidney disease and is staged further by albuminuria.
Critical actions
Creatinine must be in mg/dL (divide µmol/L by 88.4). eGFR is unreliable in acute kidney injury, extremes of muscle mass and pregnancy.
Pearls / pitfalls
- The estimate is unreliable when creatinine is changing rapidly (acute kidney injury), and at extremes of muscle mass — amputees, body-builders, frailty/cachexia — where creatinine-based eGFR can mislead.
- For dosing certain renally-cleared drugs, some guidance still uses absolute (de-indexed) GFR or Cockcroft-Gault creatinine clearance — always follow the specific drug’s recommendation rather than assuming eGFR.
- A cystatin C-based eGFR can be used to confirm or refine the estimate when a creatinine-based value is borderline or potentially inaccurate.
- A single low reading is not CKD: confirm persistence over more than three months and stage with albuminuria.
Evidence & validation
Based on the 2021 CKD-EPI creatinine equation (Inker, Eneanya, Coresh et al.), recommended by the National Kidney Foundation/ASN Task Force and reflected in KDIGO and NICE guidance for CKD assessment.
Frequently asked questions
What is a normal eGFR?
An eGFR of 90 mL/min/1.73 m² or above is normal. Values of 60–89 are only abnormal (CKD) if there is also a marker of kidney damage such as albuminuria.
How does eGFR differ from creatinine clearance or Cockcroft-Gault?
eGFR (CKD-EPI) is indexed to body surface area and is used for CKD staging. Cockcroft-Gault estimates creatinine clearance and is still specified for dosing some drugs — they are not interchangeable.
Why was race removed from the equation?
The 2021 CKD-EPI equation removed the race coefficient to provide a single, more equitable estimate of kidney function for all adults.
Does one low eGFR mean I have chronic kidney disease?
No. CKD requires the reduction (or a damage marker) to persist for more than three months; a single low value may reflect acute or reversible changes.
Can I use eGFR for drug dosing?
Sometimes, but not always — certain drugs are dosed by absolute GFR or Cockcroft-Gault creatinine clearance. Check the individual drug’s guidance, especially at low kidney function or extremes of body size.
References
- Inker LA, Eneanya ND, Coresh J, et al. New creatinine- and cystatin C-based equations to estimate GFR without race (CKD-EPI 2021). N Engl J Med. 2021;385:1737–1749.
- KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease.
- NICE NG203: Chronic kidney disease: assessment and management. 2021.
About the creator
Inker LA et al. (CKD-EPI)
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