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Blood Test Tracker

eGFR calculator from cystatin C (CKD-EPI 2012)

An estimate of how well your kidneys filter blood, worked out from your cystatin C level, age and sex, without using creatinine. Type your results in the units on your report and it works out eGFR (cystatin C) as you type, in your browser.

AI-verified against cited sources. Awaiting expert reviewLast reviewed 2026-10-03Kidneys

mg/L
In years, on the day of the blood test.
years
The equation has a version for each.

Type your results above, or fill in the example, to see eGFR (cystatin C).

Nothing you type here leaves your browser.

Educational information, not medical advice. Blood Test Tracker doesn’t diagnose or treat, and it doesn’t replace your clinician. Talk with your clinician before changing medications, supplements or care.

How it’s worked out

The formula

eGFR (mL/min/1.73 m²) = 133 × min(Scys/0.8, 1)^−0.499 × max(Scys/0.8, 1)^−1.328 × 0.996^age × 0.932 [if female]; Scys = serum cystatin C in mg/L, age in years

When the equation works

Outside these limits the calculator says so instead of giving a number.

  • Cystatin C: 0.3 to 8 mg/L
  • Age: 18 years and over

A worked example

Example numbers, not anyone’s real results, run through the same code as the calculator above.

Example inputs and the result
Cystatin C1 mg/L
Age60 years
SexFemale
eGFR (cystatin C)72 mL/min/1.73 m²

For a woman aged 60, this result is in the usual range.

What eGFR (cystatin C) tells you

eGFR stands for estimated glomerular filtration rate, a measure of how much blood your kidneys filter each minute. This version is calculated from your blood cystatin C level, your age and your sex. Cystatin C does not depend much on muscle mass, so it can be a useful alternative when creatinine may be misleading. It does have its own influences, such as body fat, smoking, inflammation and thyroid problems.

A cystatin C-based eGFR can help when a creatinine-based eGFR is likely to be off, for example in healthy people with an unusual amount of muscle. KDIGO 2024 suggests considering it in specific circumstances. It adds that using creatinine and cystatin C together (a combined eGFR) is more accurate than either alone, and it recommends the combined estimate when creatinine alone is less accurate. A large gap between the two single-marker estimates can be informative on its own.

Read the full page on eGFR (cystatin C), with what a high or low result can mean.

Usual ranges

The ranges the result above is placed on. Your own lab’s printed range comes first if it gives one.

Sources

The equation

  1. CKD-EPI Cystatin C Equation (2012), National Kidney Foundation
  2. Estimating glomerular filtration rate from serum creatinine and cystatin C, New England Journal of Medicine (2012)
3 more sources for the ranges and the explanation
  1. CSTCE - Cystatin C with Estimated Glomerular Filtration Rate (eGFR), Serum, Mayo Clinic Laboratories (via the Schneck Medical Center test catalog)
  2. KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease, Kidney International 105(4S):S117-S314 (2024)
  3. Association Between Serum Cystatin C and Thyroid Diseases: A Systematic Review and Meta-Analysis, Frontiers in Endocrinology (2021)

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. The calculator is version 1.0.0 of our code for this equation, tested against published examples. How we build and check these pages.

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