Cystatin C, Serum or Plasma Concentration
This test measures the level of cystatin C, a small protein produced by all cells in your body. It helps assess kidney function.
["Cystatin C is a simple blood test that supports kidney health monitoring."]
Key facts at a glance
- LOINC
- 21577-2
- Short code
- CDT-TRIS
- Synonyms
- CDT Trisialo/Tf MFr SerPl
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST, gold-top) or red-top tube without anticoagulant
- Units
- N/A
- Ref low
- 0
- Ref high
- 1
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–99 years
- Method
- High-Performance Liquid Chromatography (HPLC) or Capillary Electrophoresis (CE); immunonephelometry for total transferrin quantification; ratio of trisialo-transferrin to total transferrin calculated
- CPT
- 82373
- SNOMED
- 395147008
- Specimen volume
- 1.0 mL serum (minimum 0.5 mL)
- Stability
- Room temperature: 7 days; Refrigerated (2-8°C): 14 days; Frozen (-20°C or below): 30 days. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 100
- Lipemia max
- 100
- Icterus max
- 50
- TAT
- 48–120 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 fatigue, swelling, or changes in urine output. It can also be used to monitor kidney disease progression or guide treatment decisions, particularly in patients with conditions like diabetes or high blood pressure.
How Is the Test Performed?
A small blood sample is taken from a vein, usually in your arm. The blood is sent to a lab where it is analyzed to measure cystatin C levels using a specialized immunoassay method.
What Does the Result Mean?
Higher than expected levels may indicate kidney problems, while lower levels might suggest conditions affecting protein production or kidney function. Your results will be compared to standard reference ranges provided by your lab.
Common Conditions Monitored
Cystatin C is often used alongside other tests like creatinine to assess kidney function, particularly in people with chronic kidney disease, those on dialysis, or those with conditions that may impact kidney health.
Reference range
Trisialo-transferrin / Total Transferrin ratio: <1.0% (normal); 1.0-1.5% (equivocal/grey zone); >1.5% (consistent with congenital disorders of glycosylation or alcohol abuse marker)N/A
No fasting required. Abstinence from alcohol for at least 2 weeks prior to testing is recommended for accurate interpretation of alcohol-related carbohydrate-deficient transferrin patterns. Recent transfusion or acute-phase response may affect results.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: Kidney Function Assessment
Short name
Cystatin C
Frequently asked questions
What factors might affect my cystatin C levels?
How often should I get this test?
Can I prepare 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 11, 2026. · Read our editorial policy