Kidney & Electrolytes

Cystatin C Test -- A Precise Kidney Function Marker

Cystatin C is produced at a steady rate by virtually all cells in the body and is removed from the blood exclusively by the kidneys. Because its production is not significantly affected by muscle mass, diet, or sex, it provides a more accurate picture of kidney function than creatinine alone. Emerging research also links cystatin C to cardiovascular risk and new-onset diabetes.

Why Test Cystatin C?

Testing cystatin C is recommended when you want an unbiased view of kidney health -- especially if your muscle mass is unusually high or low, making creatinine less reliable. It is also valuable for anyone with risk factors such as heavy alcohol use, a nutrient-poor diet, diabetes, or cardiovascular disease. Repeated measurements help track the effect of lifestyle changes and treatment.

What Do High Cystatin C Levels Mean?

Elevated cystatin C corresponds to a decreased glomerular filtration rate (GFR) and points to reduced kidney function. Causes include chronic kidney disease, diabetes, hyperthyroidism, osteoporosis, and systemic inflammation. Recent studies also associate high cystatin C with increased risk of heart failure and mortality.

What Do Low Cystatin C Levels Mean?

Low cystatin C is rare and not well understood. It may occasionally occur in conditions involving rapid muscle loss or severe malnutrition. Discuss unexpectedly low results with your doctor.

Symptoms to Watch For

  • Reduced urine output
  • Fluid retention and swelling in the legs or ankles
  • Persistent fatigue
  • High blood pressure
  • Nausea or shortness of breath

Who Should Get Tested?

  • People with early-stage or suspected kidney disease
  • Individuals with diabetes or cardiovascular risk factors
  • Elderly people or those with low muscle mass
  • Athletes or highly muscular individuals where creatinine may be misleading
  • Anyone monitoring kidney health over time

How to Prepare for Your Test

No preparation is needed. Bring valid ID to your appointment.

Order Your Blood Test

Test your Cystatin C levels with an accredited Swedish laboratory. Results within days, reviewed by Wellth.

Cystatin C →

Frequently Asked Questions

How is cystatin C different from creatinine?
Creatinine levels are influenced by muscle mass, age, sex, and diet, which can skew results. Cystatin C is produced at a constant rate regardless of these factors, making it a more reliable kidney marker in many cases.
Can cystatin C predict heart disease?
Yes. Elevated cystatin C has been linked to increased cardiovascular risk, heart failure, and mortality in several studies, even in people without known kidney disease.
Should I test both cystatin C and creatinine?
Testing both can give a more complete picture. If the two results differ significantly, it can help your doctor pinpoint whether the issue is kidney-related or influenced by muscle mass.
What if both cystatin C and hsCRP are elevated?
This combination may indicate systemic inflammation rather than isolated kidney dysfunction. Additional inflammatory markers such as ESR or IL-6 can help clarify the situation.
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Wellth Team

Wellth

Our content is written and reviewed by Wellth, and fact-checked against peer-reviewed research and current Swedish clinical guidelines.

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Medical Disclaimer

The information on this page is provided for informational purposes only and does not constitute professional medical advice, diagnosis, or treatment. Wellth provides health information and testing services but is not a substitute for clinical care. Always consult a qualified healthcare provider if you have questions about a medical condition. If you are experiencing severe or urgent symptoms, contact your doctor or call 1177 Vårdguiden. Blood test results should be interpreted by a qualified healthcare professional in the context of your complete medical history.