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Microbiology & Infection
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Currently under review
Pending specialist review and validation.
Carcinoembryonic antigen is a protein that your body makes in small amounts. It is produced at higher levels during fetal development, then usually drops after birth. The CEA test measures this protein in your blood.
Clinicians use CEA primarily as a tumor marker, most often in people with colorectal cancer. It can also be found in some other cancers and in certain noncancer conditions. The test is usually done on a blood sample from a vein and does not typically require fasting.
CEA is most helpful for tracking how colorectal cancer responds to treatment and for monitoring after surgery or therapy. If you have been treated for cancer, your care team may check CEA over time to look for patterns that suggest response or possible recurrence. It may also be used alongside imaging and other tests to help guide decisions.
CEA is not a screening test for people without symptoms or a prior cancer diagnosis. Levels can rise due to reasons other than cancer, such as inflammation or liver problems, so results are always interpreted with your clinical history and other findings.
Your provider will look at your CEA result in context, including your diagnosis, recent treatments, and any symptoms. Changes over time often matter more than a single value. A falling level after treatment can suggest response, while a rising trend may prompt further evaluation.
Noncancer conditions and everyday factors can affect CEA. Smoking, infections, liver disease, and kidney problems can lead to higher readings. If your result is unexpected, your clinician may repeat the test, review medications and supplements, and consider imaging or endoscopy if needed. Always discuss questions about your result with your care team so you know the next steps.
Reference intervals vary by laboratory, analyzer, methodology, population, and units. The ranges shown here are for education only. Always interpret your results against the reference interval printed on your own lab report.
People who smoke often have higher baseline CEA, which can make small changes harder to interpret. Tell your care team about your smoking status so they can set appropriate expectations and track trends accurately.
Conditions such as infections, pancreatitis, inflammatory bowel disease, hepatitis, or impaired bile flow can raise CEA without cancer. Your provider will consider these when interpreting results.
Surgery, chemotherapy, radiation, or procedures that inflame or injure tissue can temporarily alter CEA. Timing the test consistently relative to treatment helps avoid misleading changes.
Certain antibodies in the blood and high-dose biotin supplements can interfere with some immunoassays. Avoid high-dose biotin for at least a day before testing when advised, and tell your provider about all supplements.
Reduced kidney clearance can increase CEA levels. If you have chronic kidney disease, your care team may rely more on trends and complementary tests.
Using the correct collection tube, prompt processing, and avoiding significant hemolysis help ensure reliable results. If pre-analytic issues occur, a repeat sample may be recommended.
Pregnancy and early life are associated with physiologic changes in CEA biology. Discuss any pregnancy or postpartum status with your clinician when reviewing results.
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