CEA clinical test significance and reference values

Reference range: RIA, ELISA: <5μg/L in adult serum; <2.5μg/L in urine.

Influencing factors:

Smokers have higher normal ranges than nonsmokers, and increased carcinoembryonic antigen levels may be caused by smoking rather than cancer.

Clinical significance:

Carcinoembryonic antigen is a protein that is undetectable in the blood of healthy people. When this protein appears in the blood of adults, it indicates the development of cancer but does not indicate the type of cancer. Carcinoembryonic antigen is commonly used to monitor patients with gastrointestinal cancers and can also be used to determine whether the cancer is benign.

The most important application of carcinoembryonic antigen is in monitoring the treatment of cancer patients. It is used to evaluate patient outcomes after surgery and monitor cancer recurrence. Carcinoembryonic antigen in blood is often used as a tumor marker. Physicians generally use the results of carcinoembryonic antigen to determine the disease stage, lesion extent, and prognosis of patients with gastrointestinal cancer, especially colorectal cancer. Carcinoembryonic antigen is also a marker of other types of cancer. It has been found to be useful in monitoring cancers of the lung, breast, liver, pancreas, stomach, and ovaries. Not all cancers produce carcinoembryonic antigen, so the carcinoembryonic antigen test should not be used for general population screening.

People with small or early-stage tumors will have very low levels of CEA on initial testing; patients with advanced tumors or those whose tumors have spread throughout the body will have higher levels. If the carcinoembryonic antigen is reduced to normal levels after treatment, it means that the tumor that produced the carcinoembryonic antigen has been eliminated. A regular increase in carcinoembryonic antigen levels is the first signal of tumor recurrence.

Elevated carcinoembryonic antigen also occurs in non-cancer-related conditions such as inflammation, cirrhosis, and peptic ulcers. In addition, smokers often have higher levels of carcinoembryonic antigen.

When cancer spreads to other organs, increased levels of carcinoembryonic antigen are detected in other body fluids, including blood. For example, if CEA is detected in cerebrospinal fluid, it means cancer has metastasized to the central nervous system.

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