Cystatin C - Quantitative Measurement
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 evaluate kidney health and may be used alongside other tests to monitor kidney function."]
Key facts at a glance
- LOINC
- 42021-6
- Short code
- CT Guided C-spine Needle loc
- Synonyms
- CT Guided C-spine Needle loc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- ct
- 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 check how well your kidneys are working, especially if you have symptoms like fatigue, swelling, or changes in urine output. It can also be used in people with diabetes, high blood pressure, or a family history of kidney disease to monitor progression or guide treatment decisions.
What to Expect Before the Test
No special preparation is usually needed, but you may be asked to fast for a few hours before the blood draw if instructed by your provider. Bring any medications you’re currently taking to your appointment.
How the Test Is Performed
A healthcare professional will draw blood from a vein in your arm using a small needle. You may feel a slight pinch, but it usually doesn’t cause discomfort. The blood sample is then sent to a lab for analysis.
What the Results Mean
Higher than expected levels of cystatin C may indicate reduced kidney function, while lower levels might suggest overhydration or other conditions. Your results will be interpreted by your provider in the context of your overall health and medical history.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Cystatin C is a reliable marker for kidney function because it’s produced by all cells and doesn’t depend on liver function or hydration status like other kidney tests. It’s often used alongside creatinine levels to better assess kidney health, especially in people with diabetes or those who have limited kidney function due to other conditions.
Short name
Cystatin C
Frequently asked questions
How long does it take to get my results?
Can I eat or drink before this test?
Is there anything I should avoid before the blood draw?
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