CKD-EPI 2021 eGFR with cystatin C
Race-free eGFR from cystatin C, alone or combined with creatinine.
Inputs
0 of 3SexUsed by the equation
years
mg/L
Optional.
Patient values are shared with every calculator.
When to use
- When creatinine may mislead: low muscle mass, amputation, cirrhosis, extremes of body size, or before narrow-margin drug dosing.
Pearls and pitfalls
- KDIGO 2024 favors the combined creatinine-cystatin equation when accuracy matters.
- Cystatin C rises with corticosteroids, thyroid disease, and inflammation.
Why use
The most accurate routine GFR estimate.
Cystatin: 133 × min(Scys/0.8, 1)^−0.499 × max(Scys/0.8, 1)^−1.328 × 0.996^age × 0.932 (female). Creatinine-cystatin: 135 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^−0.544 × min(Scys/0.8, 1)^−0.323 × max(Scys/0.8, 1)^−0.778 × 0.9961^age × 0.963 (female); κ 0.7 F, 0.9 M; α −0.219 F, −0.144 M