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Serum/Plasma Concentration of Cystatin C (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 that helps regulate cell growth. It’s often used alongside other tests to assess kidney function.

Quick summary

["Cystatin C helps evaluate kidney health and may support kidney function monitoring."]

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

Key facts at a glance

LOINC
81836-9
Short code
CTSK Mut Anl Bld/T
Synonyms
CTSK Mut Anl Bld/T
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
molgen
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your healthcare provider may order this test to check for early signs of kidney problems, especially if you have risk factors like diabetes, high blood pressure, or a family history of kidney disease. It can also be used to monitor kidney function in people already diagnosed with kidney disease.

How Is the Test Performed?

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

What Do Results Mean?

Results are compared to a general reference range to help determine if your kidneys are functioning normally. Higher than expected levels may indicate kidney problems, while lower levels are less common and usually not directly concerning.

Common Causes of Abnormal Results

Elevated cystatin C levels can be linked to kidney disease, dehydration, or certain medications. Lower levels are rare but may occur in conditions like overhydration or certain genetic factors.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Cystatin C

Frequently asked questions

Will I need to prepare for this test?
No special preparation is needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a larger kidney function panel. Always follow your healthcare provider’s instructions.
How soon will I get my results?
Results are typically available within 1–3 business days, depending on your lab. Your provider will discuss them with you during your follow-up visit.
Can I have my results explained in a different way?
Yes, if you’d like a simpler explanation or clarification, ask your healthcare provider or lab technician to break it down for you.
  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