Cystatin C in Serum

Cystatin C is a better marker of kidney function than creatinine, since it is not affected by muscle mass. It is also a top predictor of biological age.
Also known as:
S-cystatin-C
.

Cystatin C ranges

Interpret your result
"Normal" lab range for Cystatin C is between 0.61 and 0.95 mg/L:
0.61
0.95
According to Peter Attia, Cystatin C should be below 1 mg/L:
1
According to OptimalDX, Cystatin C should be between 0.62 and 0.9 mg/L:
0.62
0.9
Optimal range
Optimal range for Cystatin C appears to be between 0.55 and 0.8 mg/L:
0.3
0.55
0.8
1
2
Why this optimal range?
Preliminary range is based on functional health organizations including but not limited to those listed above.

What a low value may mean:

Common reasons for low Cystatin C:

  • Low Cystatin C is rarely clinically significant in isolation.

    Common reasons: Kidney hyperfiltration, Hypothyroidism, Bladder cancer.

    Low Cystatin C is associated with cognitive dysfunction and Alzheimer’s disease.

What a high value may mean:

Common reasons for high Cystatin C:

  • The dominant cause is reduced glomerular filtration — chronic kidney disease, acute kidney injury, or any condition impairing renal clearance.

    Several non-renal factors also raise Cystatin C independently of GFR: hyperthyroidism, obesity, chronic inflammation, corticosteroid (and other immunosuppressant) therapy, current smoking, alcohol, older age.

    Because of these confounders, Cystatin C is considered unreliable in patients with untreated thyroid disease or on chronic steroids.

Possible consequences from high Cystatin C:

  • High Cystatin C values ( > 1.08 mg/l) were associated with 50% mortality rate at 15 years.
  • Elevated Cystatin C (0.70 - 1.08 mg/l) were associated with 20% mortality rate at 15 years.

Images:

Cystatin-C increases during aging

Cystatin-C increases during aging

Participants with and without clinical risk factors for kidney disease. (diabetes, hypertension, obesity, smoking, coronary heart disease, ...)
High Cystatin C was associated with substantial rise in all-cause mortality.

High Cystatin C was associated with substantial rise in all-cause mortality.

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About the site author

My personal mission is to extend human lifespan by collectively adding 1 million years to people's lives.

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Zsolt Szabo
Zsolt Szabo
Precision Health Consultant for Longevity Clinics, Biohacker, and Software Engineer

Please send me relevant research and feedback.

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I am particularly interested in research on biomarkers associated with all-cause mortality and on defining optimal reference ranges.