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Cystatin C (Serum) Concentration

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

This test measures the level of cystatin C, a small protein produced by all cells in the body. It helps assess kidney 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
6834-6
Short code
Deprecated Cat Hair+Epith IgE Qn
Synonyms
Deprecated Cat Hair+Epith IgE Qn
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 This Test Is Done

Your doctor may order a cystatin C test to evaluate kidney function, especially if you have risk factors for kidney disease, such as high blood pressure, diabetes, or a family history of kidney problems. It can also be used alongside other tests to monitor kidney health in people with chronic conditions.

How the Test Works

A small blood sample is taken from a vein in your arm. The sample is sent to a lab where it is analyzed to measure cystatin C levels. Unlike traditional kidney function tests like creatinine, cystatin C levels are less affected by muscle mass or certain medications.

What to Expect Before the Test

No special preparation is needed for this test. You can eat and drink normally on the day of the test. If you are on blood thinners or have a history of bleeding disorders, let your doctor know before the test.

What to Expect During the Test

The test involves a simple blood draw. You may feel a slight pinch, but it usually takes only a few minutes. You can resume your normal activities immediately after.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Cystatin C

Frequently asked questions

How often should I get this test?
The frequency depends on your health condition and your doctor’s recommendations. If you have kidney-related issues or risk factors, your doctor may suggest regular monitoring. Typically, follow-up tests are scheduled based on your individual needs and medical history.
Does food or medication affect cystatin C levels?
Neither food nor most common medications typically affect cystatin C levels. However, if you are taking certain medications that could influence kidney function, inform your healthcare provider before the test.
Can cystatin C levels be affected by pregnancy?
Yes, cystatin C levels can slightly increase during pregnancy due to changes in kidney function. Your doctor may adjust the interpretation of results during pregnancy or recommend additional monitoring.
  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