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Cystatin C (Serum) Concentration, Quantitative

Published: August 9, 2026Updated: August 17, 2026

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

Quick summary

["Cystatin C helps monitor kidney health more accurately than traditional tests alone."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
82681-8
Short code
CT Guided Oral tiss Bx
Synonyms
CT Guided Oral tiss Bx
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
7
Ref high
56
Critical range
— – 500 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ct
CPT
84484
SNOMED
302773008
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 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 determining how well your kidneys are working after treatment for conditions like high blood pressure or diabetes.

What Does the Test Involve?

A blood sample is taken from a vein, usually in your arm. The sample is sent to a lab where it is analyzed to measure cystatin C levels. No special preparation is needed, but you may be asked to fast for a few hours before the test if instructed by your provider.

What Are the Results Used For?

Higher than expected cystatin C levels may indicate kidney problems, including chronic kidney disease. Lower levels might suggest kidney function is better than expected. Your provider will use these results along with other tests and your medical history to make a diagnosis or guide treatment.

What Are Common Causes of Abnormal Results?

Cystatin C levels can be affected by factors like age, muscle mass, and certain medications. Kidney diseases, infections, or dehydration can also influence results. If your levels are abnormal, your provider may recommend further testing or adjustments to your treatment plan.

Reference range

Adult males: 7-56 U/L; Adult females: 7-43 U/LN/A

Specimen: serum

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Cystatin C Blood Test

Frequently asked questions

What symptoms might I experience if my cystatin C levels are abnormal?
Abnormal cystatin C levels alone may not cause noticeable symptoms. However, if kidney function is impaired, you might experience fatigue, swelling in your legs or ankles, frequent urination, or nausea. If you notice these or other concerning symptoms, talk to your provider about further evaluation.
How often should I get this test?
The frequency depends on your health condition and treatment plan. If you have kidney disease, your provider may recommend regular monitoring to track changes in your kidney function. Follow their guidance on how often to get this test.
Can lifestyle changes affect cystatin C levels?
While lifestyle factors like diet, exercise, and hydration can influence overall health, they do not directly affect cystatin C levels. However, managing conditions like diabetes or high blood pressure through lifestyle changes can help protect kidney function and may indirectly benefit kidney health.
  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 17, 2026. · Read our editorial policy