Considerations for a carcinoembryonic antigen test include smoking, cirrhosis and other factors that can raise CEA levels in the blood of those who do not have cancer, explains Drexel University College of Medicine. A doctor must order other tests to diagnose the cause of elevated CEA levels.
Carcinoembryonic antigen is a protein found in the blood of unborn fetuses, and the levels decrease after birth. The normal range for nonsmokers is 0 to 2.5 micrograms per liter and 0 to 5 micrograms per liter for smokers, according to Drexel University College of Medicine. Levels higher than these ranges in adults can indicate certain types of cancer, such as thyroid, breast or lung, but they can also indicate other conditions, such as inflammatory bowel disease or pancreatitis. Since CEA levels are not enough to make a diagnosis, this test is not used to screen for cancer. Doctors order this test for patients who previously had cancer to check if the cancer may have returned. They may ask smokers to avoid smoking for a short time before the test.
The test involves drawing a sample of blood from a vein with a needle, a process called venipuncture. Some people may experience pain and throbbing at the site where the needle entered the skin. There is a slight risk for complications such as excessive bleeding, fainting or dizziness, hematoma, and infection, says Drexel University College of Medicine.