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Cystatin C (Serum/Plasma) Concentration

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

This test measures the level of cystatin C, a small protein produced by all cells in your body. It helps assess kidney function.

Quick summary

["Cystatin C is a simple blood test that can help check how well your kidneys are working."]

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

Key facts at a glance

LOINC
32615-7
Short code
Hycs-Cys diS SerPl-sCnc
Synonyms
Hycs-Cys diS SerPl-sCnc
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 Is This Test Done?

Your healthcare provider 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 function.

What Does a High or Low Level Mean?

Elevated cystatin C levels may indicate reduced kidney function, while lower levels might suggest overestimation of kidney health. However, results are interpreted in the context of your overall health and medical history.

How Is the Test Performed?

A blood sample is taken from a vein, usually in your arm. The sample is sent to a lab where it is analyzed to measure cystatin C concentration using a specialized immunoassay method.

What Should You Do Before the Test?

No special preparation is usually needed, but inform your provider if you are taking medications that could affect kidney function or if you have recent illnesses.

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 are typically available within 1 to 3 business days, depending on your lab’s processing time. Your healthcare provider will discuss the findings with you during your follow-up visit.
### Can diet or hydration affect cystatin C levels?
Dietary changes or hydration status may have a slight impact on creatinine levels but are less likely to affect cystatin C significantly. However, dehydration can sometimes influence kidney function indirectly, so staying well-hydrated is generally recommended for overall health.
### Is this test painful?
The blood draw for this test involves a small needle inserted into your arm, which may cause mild discomfort for a few seconds. Most people experience minimal pain afterward, and the area may feel tender for a short time.
  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