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Cystatin C Quantitative, Plasma

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

This test measures the level of cystatin C, a protein produced by all cells in your body. It helps assess your kidney function.

Quick summary

["Cystatin C is a simple blood test to check how well your kidneys are working."]

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

Key facts at a glance

LOINC
95136-8
Short code
CMV DNA Pnl Amn NAA+probe
Synonyms
CMV DNA Pnl Amn NAA+probe
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
probe-amp-tar
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 doctor may order a cystatin C test to evaluate kidney function, especially if you have risk factors for kidney disease, such as diabetes, high blood pressure, or a family history of kidney problems. It can also be used alongside other tests to monitor kidney health over time.

How Is the Test Performed?

A small blood sample is taken from a vein in your arm. The blood is sent to a lab where it is analyzed to measure cystatin C levels. This test does not require fasting.

What Do the Results Mean?

Higher than expected cystatin C levels may indicate kidney problems, while lower levels might suggest kidney function is better than expected. Your doctor will interpret the results in the context of your overall health and other tests.

What Are Common Causes of Abnormal Results?

Elevated cystatin C levels can be caused by kidney disease, muscle disorders, or certain medications. Lower levels might be seen in people with very low muscle mass or specific genetic conditions. Always discuss any concerns with your healthcare provider.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Cystatin C is a useful marker for kidney function because it is produced by all cells and does not change with diet or hydration, unlike some other kidney function tests. It is often used alongside creatinine tests to get a more accurate picture of kidney health.

Short name

Cystatin C

Frequently asked questions

Why might my cystatin C test be done regularly?
If you have a history of kidney issues, diabetes, or high blood pressure, your doctor may recommend regular cystatin C testing to monitor your kidney function and catch problems early.
How does cystatin C compare to creatinine?
Cystatin C is often used alongside creatinine because it provides a different perspective on kidney function. While creatinine is influenced by muscle mass and diet, cystatin C is more consistent and can be more accurate in some cases.
Can I eat or drink anything before this test?
No special preparation is needed for this test. You can eat and drink normally before your blood draw.
  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