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Cystatin C, Serum or Plasma, Mass Concentration

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

This test measures the level of cystatin C, a protein produced by all cells in the body. It’s often used to help assess how well your kidneys are working.

Quick summary

["Cystatin C helps monitor kidney function and may be useful in diagnosing or managing kidney disease."]

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

Key facts at a glance

LOINC
92640-2
Short code
m-CPP Ur Cfm-mCnc
Synonyms
m-CPP Ur Cfm-mCnc
Category
chemistry
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
confirm
Specimen volume
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Doctors may order a cystatin C test to check kidney function, especially if you have symptoms like fatigue, swelling in the legs, or changes in urine output. It can also be used alongside other tests to monitor kidney health in people with diabetes, high blood pressure, or a family history of kidney problems.

What Does the Test Involve?

A blood sample is taken from a vein, usually in your arm. The blood is then sent to a lab for analysis. The test measures the amount of cystatin C in your serum or plasma.

How Is the Test Performed?

The test uses a specialized lab method to measure cystatin C levels. This protein is stable in blood and doesn’t depend on muscle mass or diet, making it a reliable marker for kidney function.

What Are Common Uses?

Cystatin C is often used to estimate glomerular filtration rate (GFR), a measure of how well your kidneys filter blood. It’s particularly useful for people with mild to moderate kidney problems where traditional tests like creatinine might not be accurate.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Cystatin C

Frequently asked questions

How long does it take to get results from this test?
Results from a cystatin C test are typically available within 1 to 3 business days, depending on your lab’s processing times. Your healthcare provider will discuss the results with you during your follow-up visit.
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. However, always follow any specific instructions your healthcare provider gives you.
Is there any risk or discomfort with this test?
There may be a slight bruise or soreness at the site where the needle was inserted, but this usually goes away quickly. Rarely, you might feel a pinch or slight discomfort during the blood draw. If you have a hard time with needles, let your healthcare provider know.
  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