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Cystatin C, Serum Concentration (Mass)

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 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
16358-4
Short code
Deprecated AB-Gp Amn-mCnc
Synonyms
Deprecated AB-Gp Amn-mCnc
Category
chemistry
Sample
fluid
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
2-5 mL
Stability
Room temperature: 2h, Refrigerated: 24h
Hemolysis max
300
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your healthcare provider may order this test to evaluate kidney function, especially if you have symptoms like fatigue, swelling, or changes in urine output. It can also be used to monitor kidney disease progression or guide treatment decisions, such as for patients on certain medications or with chronic conditions like diabetes or heart disease.

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast for 8–12 hours before the test, but this depends on your healthcare provider’s instructions. Bring any medications you’re currently taking to your appointment.

What Happens During the Test?

A healthcare professional will draw blood from a vein in your arm. The process is quick and typically causes only minor discomfort. The blood sample is then sent to a lab for analysis.

What Are the Results?

Results are compared to a reference range, which can vary slightly by lab. Higher levels may indicate reduced kidney function, while lower levels may suggest overhydration or other conditions. Your provider will interpret the results in the context of your overall health.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Cystatin C

Frequently asked questions

Why might my doctor want to check this level?
Your doctor may order this test to monitor kidney health, especially if you have conditions like diabetes, high blood pressure, or a family history of kidney disease. It can also help determine if you need adjustments to medications that affect kidney function, such as certain antibiotics or chemotherapy drugs.
How often should I get this test?
The frequency depends on your health status. If you have kidney disease, your doctor may recommend regular monitoring. If you’re healthy, it might only be done if you have risk factors or symptoms. Always follow your provider’s advice.
Can I eat or drink before this test?
Typically, you should fast for 8–12 hours before the test unless instructed otherwise. Avoid caffeine or alcohol in the hours leading up to the appointment to ensure accurate results.
  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