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Cytokeratin 19 Fragment (CYFRA) in Serum/Plasma

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

This test measures tiny protein fragments of cytokeratin 19, a protein found in certain cells of the lung and other tissues. It’s often used to monitor cancer treatment progress or check for recurrence in patients with non-small cell lung cancer.

Quick summary

["CYFRA helps track lung cancer by detecting protein changes linked to tumor activity."]

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

Key facts at a glance

LOINC
18499-4
Short code
Cyto Nipple dis
Synonyms
Cyto Nipple dis
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
cyto-stain
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

What Is CYFRA Used For?

CYFRA is primarily used in the monitoring of non-small cell lung cancer (NSCLC). Doctors may order it after treatment to check if cancer has returned or if it’s responding well to therapy. It can also be used in screening for other cancers that produce cytokeratin 19, though less commonly.

How Is the Test Performed?

A blood sample is drawn from a vein, usually in your arm. The blood is then sent to a lab where it’s tested for tiny protein fragments of cytokeratin 19. Results are compared to a baseline or previous measurements to track changes over time.

What Does a High or Low Result Mean?

Elevated levels of CYFRA may suggest cancer activity, especially in lung cancer patients. However, it can also be elevated in other conditions like chronic lung disease or smoking. Low levels might indicate a positive response to treatment, but they don’t always mean cancer is gone completely.

How Often Is This Test Done?

The frequency depends on your medical history and treatment plan. If you’re being monitored for lung cancer, your doctor may order this test every few months or as needed to assess progress.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: CYFRA’s Role in Cancer Monitoring

Short name

CYFRA 25

Frequently asked questions

Why might my doctor order this test?
Your doctor may order CYFRA if you have a history of lung cancer or other cancers that produce cytokeratin 19, or if you’re undergoing treatment to monitor its effectiveness. It’s not typically used for initial diagnosis but is valuable for ongoing surveillance.
Can CYFRA alone diagnose cancer?
No, CYFRA is not a standalone test for cancer diagnosis. It’s usually used alongside other tests, like imaging scans or tumor markers, to provide a clearer picture of cancer activity.
What if my results are abnormal?
If your CYFRA levels are elevated, your doctor will likely review your medical history, recent treatments, and other test results to determine the next steps. Further testing or imaging may be needed to investigate further.
  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