Historical Cystatin C eGFR Equations
These historical 2003–2005 equations predate current IFCC standardization. Do not apply them to contemporary assays without calibration review. The four formulas are not ranked or recommended. Grubb has separate age categories above and below 14 years.
Results update as you type. Use Enter to move to the next field.Select the next field to continue.
Estimated GFR
All results in: mL/min/1.73m²
Hoek (2003)
Mainly based on adult research
—Grubb (age 14+, 2005)
Age 14+; no adjustment
—Grubb (under age 14, 2005)
Under 14; multiplier 1.384
—Filler / Lepage (2003)
Pediatric original cohort (ages 1–18)
—
Was this calculator easy to use?
Your response is saved to improve this site. Calculator inputs and results are not sent.
Thank you! You can recommend this calculator with the share button above.
Equations, age groups, calibration and sources
Historical equations
Let C be cystatin C in mg/L. All results are indexed to 1.73 m². Hoek = 80.35/C − 4.32 (mainly adult study); Grubb age ≥14 = 84.69 × C^−1.680; Grubb under 14 = 84.69 × C^−1.680 × 1.384. Filler/Lepage = 10^(1.962 − 1.123 × log10(C)), developed in children ages 1–18.
Hypothetical example
At C = 1.00 mg/L: Hoek 76.03, Grubb age ≥14 84.69, Grubb under 14 117.21, Filler 91.62 mL/min/1.73 m².
Assay and population limitations
These pre-standardization formulas used different immunoassay methods. IFCC ERM-DA471 material was introduced in 2010, and equivalence to contemporary assays has not been confirmed. Nonpositive or non-finite formulas must be shown as not calculable, not rounded to zero. Do not infer clinical diagnosis, drug dosage, or superiority from these estimates.
Review
Original full-text equation and assay verification remains incomplete. Source check date 2026-11-10.