Cystatin C levels: what's normal, high and low
A small protein cleared by the kidneys. An alternative kidney-function marker, especially useful when muscle mass is unusual.
Medically reviewed by Youmna DiStefano, MD · Last reviewed September 2026
The short answer
Cystatin C is measured with a standard blood draw; no fasting is needed. A typical reference range is 0.550 – 1.00 mg/L (age 18–49; more bands below). At TestWell it's $36.99 all-in as Kidney Function Test (Cystatin C), results in 2–4 business days, drawn at Quest or Labcorp. An out-of-range result is a prompt to look closer, not a diagnosis.
- Units
- mg/L
- Sample
- Blood draw
- Fasting
- Not required
- Results
- 2–4 business days
- Price
- $36.99
- Labs
- Quest or Labcorp · BioReference in NY/NJ
Cystatin C Reference Range
These are the typical adult reference ranges used by major US labs. Your report will include the specific range used by the lab that processed your sample.
| Population | Range |
|---|---|
| age 18–49 | 0.550 – 1.00 mg/L |
| age 50+ | 0.610 – 1.21 mg/L |
Reference ranges are educational. Always interpret your result with the specific range printed on your lab report and discuss anything outside the range with a clinician.
What your Cystatin C result may mean
Often reflects reduced kidney function. Less affected by diet and muscle mass than creatinine.
What a high Cystatin C means: causes, symptoms, next steps →Educational only — not a diagnosis. Many factors can influence a single result. Discuss anything that concerns you with a healthcare provider.
How do you get a Cystatin C test?
Order online, a licensed physician reviews the requisition, and you walk into a nearby lab for the draw. Cystatin C is available on its own or inside these panels — panels cost less per marker when you want the fuller picture.
| Option | Includes | Price |
|---|---|---|
| Kidney Function Test (Cystatin C) | This marker only | $36.99 |
| Kidney Health Panel | 4 tests | $64.99 |
| Total Body Panel | 49 tests | $499.99 |
Quest vs. Labcorp for Cystatin C: which lab should you pick?
Both are CLIA-certified national labs and the result is clinically equivalent, so pick whichever location is closer. Your report will print that lab's own reference range, which can differ slightly from the table above.
| Lab | Available | Price |
|---|---|---|
| Quest Diagnostics | Yes | $36.99 |
| Labcorp | Yes | $36.99 |
| BioReference (NY & NJ) | Yes | $22.99 |
Need help choosing a location? Use the lab finder to see draw sites near your ZIP.
Frequently asked
Often reflects reduced kidney function. Less affected by diet and muscle mass than creatinine. A single result above the reference range is a prompt to look closer with a clinician — often a repeat test and related markers — not a diagnosis on its own.
Ready to test your cystatin c?
Order in two minutes, get physician-approved, and visit a lab the same day. Starts at $36.99.