Skip to content

Cystatin C, Serum, Quantitative

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

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

Quick summary

["Cystatin C helps doctors check how well your kidneys are working."]

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

Key facts at a glance

LOINC
53967-6
Short code
Dysmorphic RBC/RBC NFr UrnS Micro
Synonyms
Dysmorphic RBC/RBC NFr UrnS Micro
Category
chemistry
Sample
urine
Container
Sterile urine container
Units
N/A
Ref low
4.2
Ref high
5.9
Critical range
2 N/A – 7 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
microscopy-light
CPT
85041
SNOMED
900000000000003001
Specimen volume
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your doctor may order this test to evaluate kidney health, 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 certain medications or dialysis planning.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm to draw a blood sample. If you’re on blood thinners, let your doctor know before the test.

What the Results Mean

Higher than expected levels may indicate kidney problems, while lower levels might suggest overhydration or other conditions. Your doctor will interpret results in the context of your overall health.

Common Causes of Abnormal Results

Elevated cystatin C can be due to kidney disease, dehydration, or certain medications. Lower levels may occur with fluid overload or conditions affecting muscle mass.

Reference range

Adult males: 4.2-5.9; Females: 3.8-5.1 x 10^12/LN/A

Specimen: urine

No special preparation required. Stay well hydrated.

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 kidney filtration. It’s often used alongside other tests, like creatinine, to assess kidney health, especially in people with diabetes or heart disease.

Short name

Cystatin C Blood Test

Frequently asked questions

Will I need to avoid certain foods or drinks before the test?
No special diet is required. However, if you’re taking medications that affect kidney function, inform your doctor before the test.
How long will it take to get my results?
Results are typically available within 1–3 business days, depending on your lab. Your doctor will discuss them with you.
Can I take my usual medications on the day of the test?
Yes, unless your doctor advises otherwise. Some medications may affect test results, so always check with your healthcare provider.
  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