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Cystatin C, Serum Concentration

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

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

Quick summary

["A simple blood test to check kidney health using a protein that stays stable in the blood."]

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

Key facts at a glance

LOINC
35983-6
Short code
CT UE-R
Synonyms
CT UE-R
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 doctor 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 for patients on dialysis or with certain medications that affect kidney function.

How Is the Test Performed?

A small blood sample is drawn from a vein, usually in your arm. The blood is sent to a lab where it is analyzed to measure cystatin C levels. This process is quick and typically requires no special preparation.

What Does the Result Mean?

Higher than expected levels may indicate kidney problems, while lower levels might suggest conditions that reduce protein production. Your doctor will interpret the result in relation to your overall health and medical history.

Common Reasons for Testing

This test is often used alongside other kidney function tests, such as creatinine, to get a more complete picture of kidney health. It is also useful for monitoring chronic kidney disease and determining how well your kidneys are filtering waste products from your blood.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Cystatin C

Frequently asked questions

What are the normal results?
There are no standard reference ranges provided here since they can vary by lab and patient factors. Your doctor will compare your result to your baseline and clinical context to determine if it is within normal limits or if further action is needed.
How soon will I get my results?
Results are typically available within 1 to 3 business days, depending on your lab’s processing time. Your doctor will contact you with the results and any follow-up instructions.
Can I eat or drink before this test?
No special preparation is needed for this blood test. You can eat and drink normally before your appointment.
  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