Cystatin C
Cystatin C is a small protein produced by all nucleated cells and cleared by glomerular filtration. Because it is largely independent of muscle mass, diet, and sex, it estimates kidney function more accurately than creatinine in elderly, frail, or very muscular individuals. Elevated levels also independently predict cardiovascular events and mortality.
Optimal range: who says what
Institutions, researchers and practitioners draw the line in different places. Each position is listed with who holds it and, where a document states it, a link. How we verify ranges.
- Named practitioner<0.91 mg/LLife Extension · Lab Testing Protocol (Suggested Optimal Ranges)Disclosure: Life Extension sells lab panels that appear in our blood-test comparisons.
- General guidance, no named sourceLower half of referenceHigher cystatin C tracks lower filtration; confirms eGFR without the muscle-mass distortion of creatinine
- Lab reference interval0.53-0.95 mg/LWhat a lab report flags against. A lab interval is not an optimal target.
Practitioner targets are individual positions, often tighter than guideline ranges. Each was checked against its article before publishing.
5 providers include this
Kidney Function
Why Cystatin C matters
More precise measure of kidney filtration, especially useful in elderly, muscular individuals, or those with abnormal creatinine. Better predictor of cardiovascular risk and mortality.
Which Providers Test Cystatin C?
Cheapest: Mito Health at $297/year. Most comprehensive: Function Health, 160+ biomarkers for $365/year.
5 panels that include it, cheapest first
| Provider | Annual Cost | Total Biomarkers | $/Biomarker |
|---|---|---|---|
| $297 | 100+ | $2.97 | |
 Superpower | $349 | 100+ | $3.49 |
 Function Health | $365 | 160+ | $2.28 |
| $895 | 100+ | $8.95 | |
| $1950 | 130+ | $15.00 |
$/Biomarker is annual cost divided by the panel's advertised biomarker count, not the price of this one test. We track 23 blood test providers (32 plans); 21 of those plans are itemized marker by marker. Compare all of them.
16 itemized panels do not include Cystatin C
WHOOP Advanced Labs · Labcorp OnDemand · Life Extension Elite · Everlywell · InsideTracker · Marek Health Base · Marek Health Comprehensive · Blueprint · Empirical Health · Oura Health Panels · SiPhox Health · Hims Labs · Healthspan · Vitality Blueprint Standard · Vitality Blueprint Elite · Ultrahuman Blood Vision Annual
11 providers not itemized in our matrix
We have not itemized these marker by marker (some sell tests one at a time), so this page cannot say whether they offer Cystatin C. Check with them directly.
Life Extension Standard · Quest Health · Ultrahuman Blood Vision · Lifeforce · Hundred Health · Personalabs · Walk-In Lab · HealthLabs · WHOOP Specialized Panels · Marek Health Essential · Vitality Blueprint Upload
Experts discussing Cystatin C
Podcast episodes where clinicians and researchers cover this marker in depth. Curated by hand; an episode is listed only when the marker is a substantial topic, not a passing mention.
- Bryan Johnson's Blueprint: The 11 Biomarkers for LongevityDisclosure: This is Bryan Johnson's podcast; Johnson owns Blueprint, which appears in our blood-test comparisons.
- Don't Die Podcast #4: The Biomarker Strategy That Made Bryan Johnson the World's Healthiest HumanDisclosure: This is Bryan Johnson's podcast; Johnson owns Blueprint, which appears in our blood-test comparisons.
- Freely Filtered Episode: Creatinine and eGFR Deep Dive
Frequently Asked Questions
What is the optimal range for Cystatin C?
Named practitioners target: <0.91 mg/L (Life Extension). General guidance without a named source: Lower half of reference (Higher cystatin C tracks lower filtration; confirms eGFR without the muscle-mass distortion of creatinine). Lab reference interval: 0.53-0.95 mg/L. That is what a lab report flags against, not an optimal target.
Which blood test providers include Cystatin C?
5 of the 21 blood testing panels we itemize marker by marker include Cystatin C in their panels. This biomarker has limited availability.
Related: YouBoost rates lifestyle and supplement interventions by evidence.
Medical Disclaimer
This information is for educational purposes only and is not medical advice. Always consult with a qualified healthcare provider about your specific health needs.
Last reviewed Sep 23, 2026 · First published Nov 30, 2025