Cystatin C eGFR Calculator — CKD-EPI 2021
Estimate glomerular filtration rate from serum cystatin C using the 2021 CKD-EPI equation. Cystatin C is independent of muscle mass, making it a useful confirmatory test when creatinine-based eGFR may mislead.
When to use it
Use to confirm CKD staging in patients with atypical muscle mass (amputees, the frail elderly, body-builders) or when an accurate GFR is needed before nephrotoxic therapy. KDIGO suggests combining creatinine and cystatin C for greatest accuracy.
Formula
eGFRcys = 133 x min(Scys/0.8,1)^-0.499 x max(Scys/0.8,1)^-1.328 x 0.996^age x 0.932 (if female).
Category
Kidney Function
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.
About NephroMind
This calculator is part of NephroMind, a free clinical decision-aid platform from the Arab Society of Nephrology and Renal Transplantation (ASNRT) — over 128 bedside nephrology calculators plus a renal drug-dosing database, coded by a practicing transplant nephrologist.