Estimate adult glomerular filtration rate using the race-free CKD-EPI 2021 creatinine equation or the separately labeled creatinine–cystatin C equation. Results are indexed to a body surface area of 1.73 m².
CKD-EPI 2021 equations
Let x = serum creatinine / κ, using creatinine in mg/dL. κ is 0.7 for the female equation parameter and 0.9 for male.
Creatinine eGFR = 142 × min(x,1)α × max(x,1)−1.200 × 0.9938age × female factor. α is −0.241 for female and −0.302 for male; the female factor is 1.012, otherwise 1.
For the combined method, let y = cystatin C / 0.8, with cystatin C in mg/L. eGFR = 135 × min(x,1)α × max(x,1)−0.544 × min(y,1)−0.323 × max(y,1)−0.778 × 0.9961age × female factor. Here α is −0.219 for female and −0.144 for male; the female factor is 0.963.
Worked example
Using age 60, the male equation parameter and creatinine 1.2 mg/dL gives 69.2311 mL/min/1.73 m² with the creatinine-only method. Adding cystatin C 1.1 mg/L gives 71.2761 mL/min/1.73 m² with the combined method. These are estimates, not measured GFR.
Frequently asked questions
Can this be used for children?
No. These adult equations are for age 18 and older. Use an appropriate pediatric method for younger patients.
Which laboratory units are accepted?
Creatinine may be entered in mg/dL or µmol/L; divide µmol/L by 88.4 to obtain mg/dL. Cystatin C uses mg/L. Use appropriately standardized laboratory assays.
Does one eGFR result diagnose kidney disease?
No. Marker influences, changing kidney function, trends and other clinical findings affect interpretation. This calculator does not classify disease or set a medication dose.
Reference: NIDDK: adult eGFR equations, CKD-EPI 2021 creatinine and combined methods.
