Elevated carcinoembryonic antigen is caused by conditions such as cancer, pancreatitis, smoking infections and cirrhosis of the liver. The normal level of CEA in an adult that does not smoke is <2.5 ng/ml, while normal level in a smoker is <5.0 ng/ml, according to MedicineNet.
Carcinoembryonic antigens are proteins that are often found in the tissues of developing babies in the womb, notes MedlinePlus. When the baby is born, the levels of this protein reduce drastically and in some cases disappear. CEA tests are often carried out to determine if an individual has a cancer. Cancers that commonly cause an increase in the levels of CEA include gastrointestinal cancer, ovarian cancer, lung cancer, breast cancer and pancreas cancer.
Individuals that often smoke are likely to have elevated levels of CEA even if they are not affected by a cancer. Such individuals may be advised to avoid smoking a few days before taking a CEA test. Continuous smoking may compromise the results of such a test. Another condition that may lead to elevated CEA is inflammatory bowel disease.
Individuals that undergo chemotherapy or radiation therapy are likely to experience a temporary rise in CEA levels. CEA tests are done through blood tests. However biopsy tissue and body fluid tests can also reveal the levels of CEA in the body.