Cystatin C, Serum Concentration
This test measures the level of cystatin C, a protein produced by all cells in the body. It helps assess kidney function.
["Cystatin C helps monitor kidney health and may be used alongside other tests to check for kidney damage or disease."]
Key facts at a glance
- LOINC
- 50049-6
- Short code
- Hemicystine SFr Hair
- Synonyms
- Hemicystine SFr Hair
- 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 a cystatin C 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, particularly in people with diabetes or high blood pressure.
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 using a specialized immunoassay method to measure cystatin C levels.
What Are Common Uses?
Cystatin C is often used in combination with other tests, such as creatinine, to estimate glomerular filtration rate (GFR), a measure of kidney function. It is particularly useful for people with conditions that may affect traditional kidney function tests.
What Might Abnormal Results Indicate?
Higher-than-normal cystatin C levels may suggest impaired kidney function or early kidney disease. Lower levels might be seen in certain medical conditions or during pregnancy. Your results will be interpreted in the context of your overall health and other tests.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: Cystatin C is a sensitive marker for kidney function because it is produced by all cells and does not vary with muscle mass or hydration status, unlike creatinine. It is often used in clinical settings to better assess kidney health in patients with chronic conditions or those who may have subtle kidney damage.
Short name
Cystatin C
Frequently asked questions
What does a cystatin C test measure?
Can cystatin C levels change with diet or exercise?
Is fasting required for this test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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