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Cystatin C, Serum or Plasma, Mass Concentration

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of cystatin C, a protein produced by all cells in your body, in your blood. It helps assess your kidneys' function.

Quick summary

["Cystatin C is a simple blood test that supports kidney health monitoring."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
105880-9
Short code
CMV DNA SerPl-aCnc
Synonyms
CMV DNA SerPl-aCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your healthcare provider may order a cystatin C test to check how well your kidneys are working. It’s often used alongside other tests, like creatinine levels, to get a clearer picture of kidney function, especially in people with diabetes, high blood pressure, or other health conditions that can affect the kidneys.

How Is the Test Performed?

A small blood sample is taken from a vein, usually in your arm. The blood is then sent to a lab for testing. The test is quick and typically done in a doctor’s office or clinic.

What Do the Results Mean?

Higher levels of cystatin C can indicate kidney problems, while lower levels may suggest kidney function is better than expected. Your results will be compared to a standard range to help your healthcare provider understand your kidney health.

Common Reasons for Testing

Cystatin C is often used to monitor kidney function in people with chronic kidney disease, those with diabetes or high blood pressure, or as part of routine check-ups if you’re at higher risk for kidney issues.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Cystatin C

Frequently asked questions

What Are My Next Steps If My Results Are Abnormal?
If your cystatin C levels are higher than expected, your healthcare provider may recommend further testing or adjustments to your treatment plan, such as monitoring kidney function more closely or managing conditions like diabetes or high blood pressure.
How Often Should I Get This Test?
The frequency of cystatin C testing depends on your health status. If you have kidney disease or risk factors, your provider may suggest testing every few months or annually. Follow their guidance for the best plan for you.
Can Diet or Medications Affect This Test?
Dietary changes or certain medications can sometimes influence kidney function indirectly, but cystatin C levels are generally stable and not strongly affected by short-term diet or common medications unless prescribed for kidney issues.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy