Cystatin C with Estimated Glomerular Filtration Rate (eGFR)
A kidney filtration marker that stays accurate when muscle mass throws off creatinine.
Consider this test if:
- Creatinine-based eGFR came back borderline and you want a second, independent estimate
- Diabetes, high blood pressure, or a family history of kidney disease and you want accurate baseline filtration
- Very high or very low muscle mass that can distort creatinine readings
- Tracking kidney function over time or checking how it responds to a medication or condition change
- HSA/FSA eligible
- Typical results in 2-5 days · Reviewed by a real clinician
- Drawn at a CLIA/CAP-accredited lab near you ·
Pre-test considerations
A simple blood draw. Overnight fasting is preferred but not strictly required; cystatin C is unaffected by diet, body mass, and most medications, which is part of its advantage over creatinine.
Video consult with your Care Team
A 1:1 call to discuss your health.
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What this test is for
Cystatin C is a small protein produced by all nucleated cells at a steady rate and freely filtered by the kidneys, so its blood level rises as filtration falls. The eGFR derived from it (using the CKD-EPI cystatin C equation with age and sex) estimates how well your kidneys are clearing waste, and it tracks early kidney decline, chronic kidney disease, and changing function during illness. Unlike creatinine, cystatin C is not affected by muscle mass, diet, or most drugs, which makes it more reliable when creatinine misleads: very muscular or malnourished people, the very elderly, those with limb loss or paralysis, and rapidly changing kidney function. It also equilibrates faster than creatinine, so it reflects acute changes sooner. If your creatinine-based eGFR is borderline or seems inconsistent with your clinical picture, cystatin C is the standard way to confirm where filtration actually stands.
Biomarkers tested
Includes 2 biomarkers
Cystatin C is a protein made by nearly every cell in your body at a steady rate and cleared exclusively by the kidneys, which makes it a cleaner marker of filtration than creatinine, since creatinine shifts with muscle mass, diet, and workouts. Rising cystatin C signals declining kidney filtration before creatinine or symptoms catch up, useful for anyone tracking kidney health alongside blood pressure, diabetes risk, or long-term NSAID or supplement use. It's especially valuable for athletes and heavily muscled people, where creatinine runs high for reasons that have nothing to do with kidney function, and for getting an early, accurate baseline on how well your kidneys are actually clearing waste.
- Specimen
- Serum or plasma
- Measures
- Mass concentration
This estimates how fast your kidneys filter blood, calculated from cystatin C instead of creatinine. Cystatin C isn't affected by muscle mass, so it gives a cleaner read on kidney function in athletes, people who are very muscular or very frail, and anyone whose creatinine-based eGFR looks off relative to how they actually feel. A result below 60 signals reduced filtration worth tracking, while pairing it with creatinine-based eGFR helps confirm whether a low number reflects true kidney decline or just muscle mass throwing off the other formula.
- Specimen
- Serum, plasma, or blood
- Method
- Cystatin C-based
- Measures
- Ratio
What you'll learn
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Insights that connect the dots. A clinician reads your whole picture, not one result in isolation, connecting family history, past results, and lifestyle into clear next steps.
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Your personalized action plan. Nutrition, supplements, and training in one clinician-reviewed protocol, updated as your results change.
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Track your trends. Upload results from any lab and see each biomarker trend over time, so you know what is working.
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Never miss a recheck. Mito tells you what is worth retesting and when, then reminds you so nothing slips.
What to expect
- 1 Book instantly
Click, book, done. Choose a convenient lab location near you. Transparent, up-front pricing.
- 2 Quick lab visit
Testing to fit your busy schedule, usually 15 minutes or less. Walk-in and appointments available.
- 3 Typical results in 2-5 days
Your results post straight to your dashboard as soon as the lab completes them.
- 4 Expert guidance
Included with Mito membership. A clinician reviews your results and your personalized action plan follows, with clear next steps.
Everything your health needs,
in one membership
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Every test at our cost
Members pay our cost on every test, with lab fees passed straight through. The full receipt is itemized, never padded.
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Continuous tracking, all in one place
Upload past labs and watch your trends over time. Every marker and visit lives in one longitudinal record, so all your care stays together.
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Year-round clinician support
Text anytime and get clinician-reviewed answers. When you want to go deeper, 1:1 consultations are available at affordable rates.
All for $9/month
Order any test or consult without joining. For $9/month, members unlock member prices, trend tracking, and year-round clinician guidance.
Mito Membership
$9 /mo
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Without membership
$0
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Personalized action plans across supplements, exercise, nutrition, and sleep
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Year-round medical support, with in-chat clinician escalation
All your health records in one personal vault, with trends and biological age tracking
Early access to new diagnostics and product releases
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Frequently asked questions
View all FAQsHow does pricing work?
Every test shows the member price next to the standard non-member price, so you can see what membership saves you. The member price is our cost, covering the lab and what it takes to run the service. It is never a profit on the test itself. Mito makes its money on the $9 membership, not on marking up your tests. Membership is $9 per month, and any applicable lab order or draw fee is itemized before you pay.
Where do I get tested?
Choose an available partner lab at checkout. If your cart contains multiple blood tests, Mito helps consolidate the eligible tests at one lab when possible. At-home kits and scans follow the collection or appointment process shown on their product page.
Is this eligible for HSA/FSA?
Yes. Eligible tests can be paid for with an HSA or FSA card at checkout.
When will I get my results?
Your results appear in your Mito dashboard after the laboratory completes processing. A clinician then reviews them before your analysis and personalized action plan are finalized. Timing varies by test, and specialty assays and at-home kits may take longer.
Do I need a doctor's order?
No. Mito provides the laboratory order when one is required, so you do not need to arrange a separate doctor visit before purchasing.
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