Also known as CKD-EPI 2021, CKD-EPI, eGFR, GFR
Estimated GFR (race-free) — kidney function reference.
Applies to / doesn’t apply to3
Applies to: Adults (≥18) with stable kidney function. The 2021 equation was developed and validated in a large pooled population without a race coefficient (Inker 2021), and is the creatinine-based eGFR equation adopted as the US reporting standard (Delgado 2021; Miller 2022).
- Acute kidney injury, or any rapidly changing or non-steady-state creatinine (the equation assumes a steady state).
- Pregnancy, in which the equation is not validated (Wiles 2019).
- Children under 18; the equation was developed and validated only in adults.
A standardized (IDMS-traceable) value, entered as measured. Low values are never rounded up.
An exact age is required — age is a term in the formula (0.9938^age), not a threshold.
Selects κ and α; a factor of 1.012 is also applied for female sex, as in the 2021 equation.
What this score estimates
Estimates glomerular filtration rate from a standardized serum creatinine, age and sex, using the 2021 race-free refit of the CKD-EPI creatinine equation. The result is reported as a whole number in mL/min/1.73 m², indexed to a standard 1.73 m² body surface area, and banded by the KDIGO G1–G5 GFR categories. It is a point-in-time estimate for screening and staging that assumes a steady-state creatinine.
Pearls & pitfalls
10
- The result is indexed to 1.73 m² body surface area. For size-dependent drug dosing it may need de-indexing to an absolute mL/min (× BSA ÷ 1.73); some product labels are written against a Cockcroft–Gault creatinine clearance instead, which is a different quantity.
- A single value is not a CKD stage. A KDIGO G-category requires the reduction to persist for at least three months, together with other markers of kidney damage (KDIGO 2024).
- Creatinine reflects muscle mass, so the estimate is less accurate at extremes of body habitus: above-knee amputation, paralysis or spinal-cord injury, sarcopenia, cachexia, severe malnutrition, or extreme muscularity (KDIGO 2024).
- Creatine supplements and a high-protein or red-meat intake raise serum creatinine independently of filtration, which makes the estimate read low.
- Drugs that inhibit tubular secretion of creatinine raise serum creatinine without changing true GFR, so the estimate falls even though kidney function has not.
- Removing race did not remove all bias. In the development validation set the equation underestimated measured GFR in Black adults (median about 3.6 mL/min/1.73 m²) and overestimated it in non-Black adults (median about 3.9), and about 13% of estimates fell more than 30% from measured GFR (Inker 2021).
- Performance varies by cohort. Some external cohorts reported lower accuracy than in the development set, for example about 76% of estimates within 30% of measured GFR in a Korean cohort (Jeong 2023) and about 68% in a European kidney-transplant cohort (Delanaye 2022); a large US cohort found little overall change from the prior equation (Meeusen 2022). Metrics should not be assumed to transfer across populations.
Risk factors the score does not count:
- Body size is not used; the result is indexed to a standard 1.73 m², not de-indexed to the individual.
- Race is not used; the 2021 refit removed the race coefficient that the 2009 equation applied.
- Cystatin C is not used; creatinine alone is first-line, and a cystatin-C-based estimate is a separate confirmatory test.
What the guidelines say
1
This calculator provides the 2021 CKD-EPI creatinine equation only. That equation is the race-free, creatinine-based eGFR recommended for adult reporting in the United States (Delgado 2021). It superseded the earlier 2009 race-based equation, consistent with KDIGO 2024 guidance that race should not be used in computing eGFR. Cystatin C is recommended especially to confirm eGFR when a creatinine-based estimate is likely inaccurate or drives an important decision, and combining creatinine and cystatin C is more accurate than either marker alone (Delgado 2021; KDIGO 2024).
Guideline positions are stated as published. Curie.MD Calc does not publish treatment direction.
Where this comes from
9
Bands
References
- Inker LA, Eneanya ND, Coresh J, et al. New creatinine- and cystatin C-based equations to estimate GFR without race. N Engl J Med. 2021;385(19):1737-1749. View source ↗
- Miller WG, Kaufman HW, Levey AS, et al. National Kidney Foundation Laboratory Engagement Working Group recommendations for implementing the CKD-EPI 2021 race-free equations. Clin Chem. 2022;68(4):511-520. View source ↗
- Kidney Disease: Improving Global Outcomes (KDIGO) CKD Work Group. KDIGO 2024 clinical practice guideline for the evaluation and management of chronic kidney disease. Kidney Int. 2024;105(4S):S117-S314. View source ↗
- Stevens PE, Levin A; KDIGO CKD Guideline Development Work Group. Evaluation and management of chronic kidney disease: synopsis of the KDIGO 2012 clinical practice guideline. Ann Intern Med. 2013;158(11):825-830. View source ↗
- Delgado C, Baweja M, Crews DC, et al. A unifying approach for GFR estimation: recommendations of the NKF-ASN Task Force on reassessing the inclusion of race in diagnosing kidney disease. J Am Soc Nephrol. 2021;32(12):2994-3015. View source ↗
- Meeusen JW, Kasozi RN, Larson TS, Lieske JC. Clinical impact of the refit CKD-EPI 2021 creatinine-based eGFR equation. Clin Chem. 2022;68(4):534-539. View source ↗
- Jeong TD, Hong J, Lee W, Chun S, Min WK. Accuracy of the new creatinine-based equations for estimating glomerular filtration rate in Koreans. Ann Lab Med. 2023;43(3):244-252. View source ↗
- Delanaye P, Vidal-Petiot E, Björk J, et al. The new 2021 CKD-EPI equation without race in a European cohort of renal transplanted patients. Transplantation. 2022;106(12):2443-2447. View source ↗
- Wiles K, Chappell L, Clark K, et al. Clinical practice guideline on pregnancy and renal disease. BMC Nephrol. 2019;20(1):401. View source ↗