--- title: "Cystatin C / eGFR Kidney Test — Evidence, Benefits & Where… | Magellan" description: "Cystatin C / eGFR Kidney Test — Cystatin C is a low-molecular-weight protein produced at a nearly constant rate by all nucleated cells, freely filtered…" url: "https://magellanlongevity.com/p/157.md" canonical: "https://magellanlongevity.com/p/157.html" html: "https://magellanlongevity.com/p/157.html" type: "product" section: "Diagnostics & Epigenetic Tests" evidence_grade: "Measurement tool" evidence_tier: "tool" citations: 18 product_id: 157 price_usd: 55 updated: 2026-09-02 author: "Gabriel Radu, DO" author_credentials: "Physiatrist (PM&R). NY medical license 275110. NPI 1376861765." publisher: "Magellan Longevity" content_format: "markdown" license: "Educational content — not medical advice" --- # Cystatin C / eGFR Kidney Test [Home](https://magellanlongevity.com/) › [Diagnostics & Epigenetic Tests](https://magellanlongevity.com/c/2.md) › Cystatin C / eGFR Kidney Test **HTML version:** https://magellanlongevity.com/p/157.html · **In the Magellan app:** https://magellanlongevity.com/#/product/157 ## Key facts | Field | Value | | --- | --- | | Product | Cystatin C / eGFR Kidney Test | | Category | [Diagnostics & Epigenetic Tests](https://magellanlongevity.com/c/2.md) | | Evidence grade | Measurement tool (B) | | Peer-reviewed citations | 18 | | Typical listed price | $55.00 (check the live price) | | Where to buy | [Search Amazon](https://www.amazon.com/s?k=Cystatin%20C%20%2F%20eGFR%20Kidney%20Test&tag=magellanlong-20) | | Catalog ID | 157 | ## What it is Cystatin C is a low-molecular-weight protein produced at a nearly constant rate by all nucleated cells, freely filtered by the kidney's glomeruli and then reabsorbed and catabolized by the tubules, so its blood concentration reflects the glomerular filtration rate (GFR). Unlike serum creatinine, cystatin C is largely independent of muscle mass, diet, age, and sex, so cystatin C-based estimated GFR (eGFRcys), alone or combined with creatinine in the 2021 race-free CKD-EPI equations, can estimate filtration more accurately in many people and flags more chronic kidney disease than creatinine alone (13.7% vs 9.7% below an eGFR of 60 in general-population cohorts). The KDIGO 2024 guideline recommends estimating GFR from both markers together when cystatin C is available, cementing its role as the standard confirmatory measure of kidney function. ## Its role in longevity Across large cohorts and meta-analyses, cystatin C-based eGFR is at least as accurate as creatinine-based eGFR and is more strongly associated with death, cardiovascular events, and end-stage kidney disease—in one ~90,750-person consortium meta-analysis it markedly improved risk reclassification for death—and it independently predicts mortality in the general population and in heart failure, with particular value in older adults and people with atypical muscle mass. Evidence is not uniform (cystatin C did not outperform creatinine in a sub-Saharan African validation), and levels are themselves influenced by thyroid dysfunction, corticosteroids, obesity, smoking, and inflammation; the test also costs more than creatinine. This evidence describes the cystatin C biomarker and the eGFR equations themselves, not this specific commercial test product. ## Evidence grade: Measurement tool - **What the grade means:** Graded as an instrument: how accurately it measures, and whether measuring it changes anything. - **Dose used in studies:** Not a routine self-monitoring test. Reasonable once if you have a specific reason to think a creatinine-based eGFR is misleading you - unusually high or low muscle mass, or a creatinine result you are trying to make sense of. Otherwise this belongs to whoever is already following your kidney function. - **What this grade does not say:** Cystatin C genuinely outperforms creatinine alone. It is less dependent on muscle mass, the combined creatinine-cystatin C equation estimates GFR more accurately than either marker by itself, and where the two estimates disagree the cystatin C-based number is the one that tracks mortality and kidney outcomes - a large meta-analysis of that discordance makes the point clearly, and KDIGO now recommends cystatin C as a confirmatory test. That is exactly why it is a poor fit for a consumer kit: cystatin C earns its keep as a second, confirmatory measurement read alongside a creatinine, a urine albumin-to-creatinine ratio and your history, and an eGFR from a mailed sample with none of that context is a number without a denominator. It is also affected by things other than filtration - thyroid status, corticosteroids, body composition - so an abnormal result here leads directly to a clinician and a proper panel, which is a fair argument for starting there. ## In the news - **NKF and ASN Release New Way to Diagnose Kidney Diseases** — National Kidney Foundation 2021 [Read it](https://www.kidney.org/press-room/nkf-and-asn-release-new-way-to-diagnose-kidney-diseases) > The task force also recommended increased use of cystatin C combined with serum (blood) creatinine, as a confirmatory assessment of GFR or kidney function. - **Changes to eGFR Calculation and What that Means for People Living with Kidney Disease** — National Kidney Foundation 2026 [Read it](https://www.kidney.org/news-stories/changes-to-egfr-calculation-and-what-means-people-living-kidney-disease) > The Task Force also recommended increased use of cystatin C combined with creatinine for a reliable way to check kidney function. ## The research Peer-reviewed studies on the active compound. Quotes are verbatim from the cited abstract. Research describes the active mechanism and is not a claim about this specific product. ### Cited studies 1. **Evidence: Cystatin C-based eGFR** JAMA 2023 · [PMID 37787795](https://pubmed.ncbi.nlm.nih.gov/37787795/) · [DOI 10.1001/jama.2023.17002](https://doi.org/10.1001/jama.2023.17002) > lower eGFR was associated with increased rates of adverse outcomes 2. **Cystatin C Is a Predictor for Long-Term, All-Cause, and Cardiovascular Mortality in US Adults With Metabolic Syndrome** J Clin Endocrinol Metab 2024 · [PMID 38597157](https://pubmed.ncbi.nlm.nih.gov/38597157/) · [DOI 10.1210/clinem/dgae225](https://doi.org/10.1210/clinem/dgae225) > Patients with elevated cystatin C have a higher risk of all-cause, cardiovascular, and cancer death 3. **Cystatin C versus creatinine in determining risk based on kidney function.** N Engl J Med 2013 · [PMID 24004120](https://pubmed.ncbi.nlm.nih.gov/24004120/) · [DOI 10.1056/NEJMoa1214234](https://doi.org/10.1056/NEJMoa1214234) > The use of cystatin C alone or in combination with creatinine strengthens the association between the eGFR and the risks of death and end-stage renal disease across diverse populations. 4. **New Creatinine- and Cystatin C-Based Equations to Estimate GFR without Race.** N Engl J Med 2021 · [PMID 34554658](https://pubmed.ncbi.nlm.nih.gov/34554658/) · [DOI 10.1056/NEJMoa2102953](https://doi.org/10.1056/NEJMoa2102953) > New eGFR equations that incorporate creatinine and cystatin C but omit race are more accurate and led to smaller differences between Black participants and non-Black participants than new equations without race with either creatinine or cystatin C alone. 5. **Glomerular filtration rate by differing measures, albuminuria and prediction of cardiovascular disease, mortality and end-stage kidney disease.** Nat Med 2019 · [PMID 31700174](https://pubmed.ncbi.nlm.nih.gov/31700174/) · [DOI 10.1038/s41591-019-0627-8](https://doi.org/10.1038/s41591-019-0627-8) > We show that eGFRcys is most strongly associated with CVD and mortality, and, along with albuminuria, adds predictive discrimination to current CVD risk scores, whilst traditional creatinine-based measures are weakly associated with risk. 6. **Cystatin C concentration as a risk factor for heart failure in older adults.** Ann Intern Med 2005 · [PMID 15809461](https://pubmed.ncbi.nlm.nih.gov/15809461/) · [DOI 10.7326/0003-4819-142-7-200504050-00008](https://doi.org/10.7326/0003-4819-142-7-200504050-00008) > The cystatin C concentration is an independent risk factor for heart failure in older adults and appears to provide a better measure of risk assessment than the serum creatinine concentration. 7. **Cystatin C as a biomarker for estimating glomerular filtration rate.** Curr Opin Nephrol Hypertens 2015 · [PMID 26066476](https://pubmed.ncbi.nlm.nih.gov/26066476/) · [DOI 10.1097/MNH.0000000000000115](https://doi.org/10.1097/MNH.0000000000000115) > Use of serum cystatin C avoids the limitations related to both diet and muscle mass that affect serum creatinine. Cystatin C may be more accurate than serum creatinine in estimating GFR, and is more strongly associated with all-cause mortality and cardiovascular events. 8. **Kidney Disease, Race, and GFR Estimation.** Clin J Am Soc Nephrol 2020 · [PMID 32393465](https://pubmed.ncbi.nlm.nih.gov/32393465/) · [DOI 10.2215/CJN.12791019](https://doi.org/10.2215/CJN.12791019) > We also suggest mindful use of cystatin C as a confirmatory test as well as clearance measurements. 9. **Cystatin C-based CKD-EPI estimated glomerular filtration rate equations as a better strategy for mortality stratification in acute heart failure: A STROBE-compliant prospective observational study.** Medicine (Baltimore) 2020 · [PMID 33126378](https://pubmed.ncbi.nlm.nih.gov/33126378/) · [DOI 10.1097/MD.0000000000022996](https://doi.org/10.1097/MD.0000000000022996) > In patients with AHF, our study demonstrates the eGFR calculated by CKD-EPI cystatin C-based equation improved the risk stratification of mortality over both creatinine-based and creatinine/cystatin C-based equations. 10. **Impact of cystatin C-derived glomerular filtration rate in patients undergoing transcatheter aortic valve implantation.** Front Cardiovasc Med 2023 · [PMID 37187794](https://pubmed.ncbi.nlm.nih.gov/37187794/) · [DOI 10.3389/fcvm.2023.1035736](https://doi.org/10.3389/fcvm.2023.1035736) > eGFR (cystatin C) was associated with 3-year all-cause mortality in patients who underwent TAVI, and it was superior to eGFR (creatinine) as a prognostic biomarker. 11. **Glomerular filtration rate estimated using creatinine, cystatin C or both markers and the risk of clinical events in HIV-infected individuals.** HIV Med 2013 · [PMID 24024499](https://pubmed.ncbi.nlm.nih.gov/24024499/) · [DOI 10.1111/hiv.12087](https://doi.org/10.1111/hiv.12087) > Of the three CKD-EPI GFR equations, GFR(cys) had the strongest associations with mortality, CVE and OD. 12. **A Meta-Analysis on the Performance of Cystatin C- versus Creatinine-based eGFR Equations in Predicting Vancomycin Clearance.** J Korean Med Sci 2020 · [PMID 32959542](https://pubmed.ncbi.nlm.nih.gov/32959542/) · [DOI 10.3346/jkms.2020.35.e306](https://doi.org/10.3346/jkms.2020.35.e306) > Cystatin C-based eGFR equations are better than creatinine-based eGFR equations in predicting the clearance of vancomycin. 13. **Performance of creatinine- or cystatin C-based equations to estimate glomerular filtration rate in sub-Saharan African populations.** Kidney Int 2019 · [PMID 30910379](https://pubmed.ncbi.nlm.nih.gov/30910379/) · [DOI 10.1016/j.kint.2018.11.045](https://doi.org/10.1016/j.kint.2018.11.045) > The creatinine-based FAS and CKD-EPI equations performed reasonably well and were comparable when GFR was ≥ 60 mL/min/1.73m. Cystatin C did not improve performance. 14. **Difference between kidney function by cystatin C versus creatinine and association with muscle mass and frailty.** J Am Geriatr Soc 2024 · [PMID 38819605](https://pubmed.ncbi.nlm.nih.gov/38819605/) · [DOI 10.1111/jgs.19014](https://doi.org/10.1111/jgs.19014) > Higher eGFRDiff is associated with lower odds of frailty among late-life men. 15. **Association Between Estimated Glomerular Filtration Rate Based on Cystatin C and Grip Strength in Community-Dwelling Japanese Older Adults.** J Gerontol A Biol Sci Med Sci 2021 · [PMID 32971533](https://pubmed.ncbi.nlm.nih.gov/32971533/) · [DOI 10.1093/gerona/glaa240](https://doi.org/10.1093/gerona/glaa240) > Low kidney function as assessed by eGFRcys was associated with muscle weakness in community-dwelling Japanese older adults. 16. **Cystatin C enhances glomerular filtration rate estimating equations in kidney transplant recipients.** Am J Nephrol 2014 · [PMID 24457184](https://pubmed.ncbi.nlm.nih.gov/24457184/) · [DOI 10.1159/000357594](https://doi.org/10.1159/000357594) > eGFR (CKD-EPI-Creat+CysC) is more precise and reflects GFR change over time reasonably well. 17. **Cystatin C estimated glomerular filtration rate and all-cause and cardiovascular disease mortality risk in the general population: AusDiab study.** Nephrology (Carlton, Vic.) 2017 · [PMID 26938304](https://pubmed.ncbi.nlm.nih.gov/26938304/) > In a general-population cohort, cystatin C-based eGFR independently predicted all-cause and cardiovascular mortality. 18. **Cystatin C for predicting all-cause mortality and rehospitalization in patients with heart failure: a meta-analysis.** Bioscience reports 2019 · [PMID 30643006](https://pubmed.ncbi.nlm.nih.gov/30643006/) > Meta-analysis: elevated cystatin C was associated with worse all-cause mortality and rehospitalization outcomes in patients with heart failure. ## Where to buy [Search Amazon for Cystatin C / eGFR Kidney Test](https://www.amazon.com/s?k=Cystatin%20C%20%2F%20eGFR%20Kidney%20Test&tag=magellanlong-20) — affiliate search link. ## Structured data ```json {"@context":"https://schema.org","@graph":[{"@type":"ItemPage","@id":"https://magellanlongevity.com/p/157.html#page","url":"https://magellanlongevity.com/p/157.html","name":"Cystatin C / eGFR Kidney Test","description":"Cystatin C is a low-molecular-weight protein produced at a nearly constant rate by all nucleated cells, freely filtered by the kidney's glomeruli and…","inLanguage":"en","isPartOf":{"@type":"WebSite","name":"Magellan Longevity","url":"https://magellanlongevity.com/"},"author":{"@type":"Person","name":"Gabriel Radu, DO","jobTitle":"Physiatrist (PM&R)","identifier":[{"@type":"PropertyValue","name":"NPI","value":"1376861765"},{"@type":"PropertyValue","name":"NY medical license","value":"275110"}]},"publisher":{"@type":"Organization","name":"Magellan Longevity","url":"https://magellanlongevity.com/"},"encoding":{"@type":"MediaObject","encodingFormat":"text/markdown","contentUrl":"https://magellanlongevity.com/p/157.md"},"dateModified":"2026-09-02"},{"@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://magellanlongevity.com/"},{"@type":"ListItem","position":2,"name":"Diagnostics & Epigenetic Tests","item":"https://magellanlongevity.com/c/2.html"},{"@type":"ListItem","position":3,"name":"Cystatin C / eGFR Kidney Test","item":"https://magellanlongevity.com/p/157.html"}]},{"@type":"Product","@id":"https://magellanlongevity.com/p/157.html#product","name":"Cystatin C / eGFR Kidney Test","category":"Diagnostics & Epigenetic Tests","url":"https://magellanlongevity.com/p/157.html","description":"Cystatin C is a low-molecular-weight protein produced at a nearly constant rate by all nucleated cells, freely filtered by the kidney's glomeruli and then reabsorbed and catabolized by the tubules, so its blood concentration reflects the glomerular filtration rate (GFR). 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Nothing here is intended to diagnose, treat, cure, or prevent any disease. Talk to your physician before starting any supplement or device, especially if you are pregnant, nursing, or taking medication. Editorial firewall: evidence grades are assigned from the published research and are independent of any affiliate commission. As an Amazon Associate, Magellan Longevity earns from qualifying purchases. Reviewed for accuracy by a board-certified physician (DO).