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Cystatin C, Lower Respiratory Tract Specimen Probe

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

This test measures cystatin C, a protein that helps monitor kidney function. A respiratory probe sample may be used to check for infections or inflammation in your lungs.

Quick summary

["Cystatin C can reflect kidney health and help assess lung health in certain conditions."]

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

Key facts at a glance

LOINC
88558-2
Short code
CMV DNA Lower resp Ql NAA+probe
Synonyms
CMV DNA Lower resp Ql NAA+probe
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
probe-amp-tar
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 if you have symptoms like persistent cough, shortness of breath, or suspected lung infection. It can also help evaluate kidney function indirectly, especially in people with chronic conditions like diabetes or heart disease.

What Does the Sample Look Like?

The sample is collected from a respiratory probe, which is a small tube inserted into your airway to gather fluid from your lungs. This is typically done in a hospital setting under medical supervision.

What Does the Result Mean?

Higher levels of cystatin C may indicate kidney problems or inflammation in the lungs. Lower levels might suggest normal kidney function or reduced inflammation. Your results will be interpreted by your healthcare provider based on your overall health and symptoms.

How Is This Test Performed?

The test involves inserting a probe into your airway to collect fluid. The fluid is then sent to a lab for analysis. The lab measures cystatin C levels using a sensitive immunoassay method.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Cystatin C (Respiratory Probe)

Frequently asked questions

What does a cystatin C test in respiratory fluid tell me about my lungs?
It can help identify inflammation or infection in your lungs by measuring cystatin C levels, which may rise during respiratory issues. This test is not a direct measure of lung function but can support diagnosis alongside other tests.
How is the respiratory probe sample different from a blood test?
The respiratory probe sample collects fluid directly from your lungs, while a blood test measures cystatin C in your bloodstream. Both can be used to assess kidney function indirectly, but the respiratory sample focuses on lung-related inflammation.
Can I eat or drink before this test?
You may need to follow specific instructions from your healthcare provider. Generally, avoid food or liquids for a short period before the procedure to ensure accuracy, but always confirm with your 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 16, 2026. · Read our editorial policy