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Cystatin C, Serum Concentration (Quantitative)

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

This test measures the level of cystatin C in your blood, a protein that 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 diagnose or track kidney disease."]

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

Key facts at a glance

LOINC
87023-8
Short code
Guided Unsp region Absc drain cath exch
Synonyms
Guided Unsp region Absc drain cath exch
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
imaging-modality
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?

Doctors may order a cystatin C test to evaluate kidney function, especially if you have symptoms like fatigue, swelling, or changes in urine output. It’s also useful for monitoring kidney disease progression or response to treatment, particularly in people with diabetes or high blood pressure.

Who Might Need This Test?

You might need this test if you have risk factors for kidney problems, such as diabetes, high blood pressure, a family history of kidney disease, or if you’re taking medications that can affect kidney function.

What to Expect Before the Test

No special preparation is usually needed, but your doctor may advise you to stop certain medications or fasting, depending on your specific situation. Bring any recent medications or supplements you’re 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.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Cystatin C Blood Test

Frequently asked questions

How long does it take to get results?
Results are usually available within a few days to a week, depending on your lab’s processing times. Your doctor will discuss the findings with you during your follow-up visit.
What does a high or low cystatin C level mean?
A high cystatin C level often suggests impaired kidney function, while a low level may indicate overhydration or other conditions. Your doctor will interpret results in the context of your overall health and other test results.
Can diet or medications affect cystatin C levels?
Dietary changes alone rarely affect cystatin C levels, but certain medications (e.g., some antibiotics or diuretics) may influence kidney function indirectly. Always inform your doctor about all medications you’re taking.
  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