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Cystatin C, Serum Concentration

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

This test measures the level of cystatin C, a protein produced by nearly all cells in your body. It helps assess how well your kidneys are filtering waste from your blood.

Quick summary

["Cystatin C helps monitor kidney function and may be used alongside other tests to check for kidney disease."]

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

Key facts at a glance

LOINC
96396-7
Short code
CMV DNA Spec NAA+probe-Log IU
Synonyms
CMV DNA Spec NAA+probe-Log IU
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 this test to evaluate kidney function, especially if you have symptoms like swelling, fatigue, or changes in urine output. It can also be used to monitor kidney disease progression or guide treatment decisions, such as adjusting medications that affect kidney health.

What Does a Result Mean?

Higher than expected levels might suggest kidney problems, while lower levels may indicate conditions like muscle wasting or certain genetic disorders. Your doctor will interpret results in the context of your overall health and other tests.

How Is the Test Performed?

A blood sample is drawn from a vein, usually in your arm. The blood is then sent to a lab for analysis using a specialized method to measure cystatin C concentration.

Preparation for the Test

No special preparation is needed, but inform your doctor about any medications you’re taking, as some may affect kidney function or test results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Cystatin C

Frequently asked questions

Cystatin C is a more accurate marker than traditional tests like creatinine for assessing kidney function, especially in people with muscle mass variations or early-stage kidney disease. It can also help detect kidney issues before symptoms appear, making it useful for long-term monitoring in high-risk individuals.
This test is often used alongside other kidney function tests (like creatinine clearance) to get a fuller picture of kidney health. It may be particularly helpful in people with diabetes, hypertension, or a family history of kidney disease.
What Are Common Causes of Abnormal Results?
Elevated cystatin C levels may indicate kidney damage, inflammation, or certain infections. Lower levels might be linked to muscle loss, malnutrition, or specific genetic conditions. Always discuss any changes with your healthcare provider.
How Often Should I Get This Test?
Your doctor will determine how often you need this test based on your health status, medical history, and any kidney-related conditions. Regular monitoring may be recommended if you have chronic kidney disease or other risk factors.
  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