Carcinoembryonic antigen blood test
The carcinoembryonic antigen (CEA) test measures the level of CEA in the blood. CEA is a protein normally found in the tissue of a developing baby in the womb. The blood level of this protein disappears or becomes very low after birth. In adults, an abnormal level of CEA may be a sign of cancer.
How to Prepare for the Test
Smoking may increase the CEA level. If you smoke, your doctor may tell you to avoid doing so for a short time before the test.
How the Test will Feel
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging sensation. Afterward, there may be some throbbing or a slight bruise. These soon go away.
Why the Test is Performed
This test is done to monitor the response to treatment and then to check for the return of colon and other cancers such as medullary thyroid cancer and cancers of the rectum, lung, breast, liver, pancreas, stomach, and ovaries.
It is not used as a screening test for cancer and should not be done unless a diagnosis of cancer has been made.
The normal range is 0 to 2.5 micrograms per liter (mcg/L). In smokers, the normal range is 0 to 5 mcg/L.
In smokers, slightly higher values may be considered normal.
What Abnormal Results Mean
A high CEA level in a person recently treated for certain cancers may mean the cancer has returned. A higher than normal level may be due to the following cancers:
Higher than normal CEA level alone cannot diagnose a new cancer. Further testing is needed.
An increased CEA level may also be due to:
Veins and arteries vary in size from one person to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
- Excessive bleeding (rare)
- Fainting or feeling lightheaded
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
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Lee P, Jain S, Bowne WB, Pincus MR, McPHerson RA. Diagnosis and management of cancer using serologic and tissue tumor markers. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 73.