Cystatin C
A protein every cell makes, cleared by your kidneys at a steady rate.
Also printed asCys C · CysC
What it measures
A kidney filter marker that, unlike creatinine, is not affected by how much muscle you carry.
Settles the question when a muscular or very slight person has a creatinine that does not fit the clinical picture.
Why it matters for how long you stay well
Because it sidesteps muscle mass, it gives a truer read of kidney filtering in people who are very muscular or very frail, and that honesty matters most in the years when decisions get made.
How it shows up in daily life
You will not feel it. Its value is that it does not care whether you are heavily built or very slight.
High and low readings
When it reads high
Kidney filtering may genuinely be reduced.
When it reads low
Low is fine.
What moves it
Daily life
- thyroid activity
- long-running inflammation
- smoking
- weight
Medicines known to shift it
- steroids (raise it)
Listed so a result can be read in context. It is not advice to start, stop or change any medicine; that decision belongs with your physician.
Common questions
What does Cystatin C measure?
A kidney filter marker that, unlike creatinine, is not affected by how much muscle you carry. Settles the question when a muscular or very slight person has a creatinine that does not fit the clinical picture.
What does a high Cystatin C result usually mean?
Kidney filtering may genuinely be reduced.
What does a low Cystatin C result usually mean?
Low is fine.
What is the usual reference range for Cystatin C?
A broad adult reference band is 0.5–1 mg/L. Labs differ, so read your result against the band printed on your own report.
Educational only, not a diagnosis. A single number means little without your history and the rest of your panel, so discuss your own results with your physician.
Typical adult reference band
- Adults
- 0.5–1 mg/L
Labs differ. The band printed on your own report is the one that applies to your result.
Reported in mg/L
Ageing relevance
5/5
A direct input to a validated biological-age algorithm.
Worth knowing
Every cell in your body makes it at a steady rate, so it barely cares how much muscle you carry.
Have a report with this marker on it? Read it in context.
Upload it to Oraia, our health-intelligence tool, for a plain-language read of your markers that a Genoryx doctor can review.
Your biological age is a number you can measure.
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