CEA Test
A CEA test measures how much of a specific protein called carcinoembryonic antigen (CEA) you have.
A CEA test measures how much of a specific protein called carcinoembryonic antigen (CEA) you have. Healthy fetuses have high levels of this protein because CEA helps cells divide quickly, leading to more rapid growth. After birth, however, levels decrease quickly. Adults have very little if any CEA in their body. If CEA is present, however, it may be a tumor marker . Tumor markers are substances that are often made by cancer cells or by normal cells in response to certain types of cancer. The types of cancer that may cause high levels of CEA include those of the: Colon and rectum (colorectal or bowel cancer) Prostate Ovary Lung Thyroid Liver Pancreas Breast However, other noncancerous conditions may also cause high CEA levels. These include: Gastritis and stomach ulcers Chronic obstructive pulmonary disease ( COPD ) Liver diseases like cirrhosis , gallstones , or steatotic liver disease Diverticulitis Diabetes Autoimmune or inflammation diseases such as Crohn's disease Most CEA tests use a sample of your blood to measure your CEA level. Sometimes the test uses a sample of fluid from your spine, chest, or abdomen (belly), but this is less common. Other names: CEA assay, CEA blood test, carcinoembryonic antigen test
Why is this test ordered? A CEA test is mostly used in people who have been diagnosed with cancers that often increase CEA levels. The most common of these is colorectal cancer. If you've been diagnosed with a cancer that may increase your CEA level, you may need CEA testing: Before treatment to help you and your provider understand how serious your cancer is and what treatment would be helpful. Your provider may also want to get a measurement of your CEA level before treatment so that they can compare it to your CEA level after treatment. During cancer treatment to see if the treatment is working. After treatment to check whether cancer has come back. You may need to have tests on a regular schedule. Depending on your cancer's type and stage (how advanced it is), you may need to have follow-up tests every 3-6 months during the first 5 years after treatment.
Clinical Interpretation
To understand your CEA test results, your provider will consider the results of other tests and exams. Ask your provider to explain what your test results mean for your health and treatment. If you had a test before starting cancer treatment , in general: A low level of CEA may mean your tumor is small and the cancer has not spread to other parts of your body. But because some cancers don't make much CEA, your provider may use other tests to learn more about how much cancer you have and if it's spread. A high level of CEA may mean you have a larger tumor and/or your cancer has spread. You'll need other tests to confirm how serious your cancer is. If you had a test to monitor your cancer during or after treatment , your provider will compare your current CEA test results with your past test results. In general: Decreases in CEA over time often mean that treatment is working. Increases in CEA or high levels that stay high may mean that treatment isn't working. For example, if you had surgery for colorectal cancer, high levels may mean that the entire tumor wasn't removed or the cancer is growing back. Decreases in CEA after treatment followed by increases may mean cancer has come back. CEA levels that remain high or increase after treatment don't always mean that treatment isn't working, or cancer is growing. So, if your CEA levels don't come down, your provider will likely order other tests to find out why. Labs use different methods to measure CEA, which can affect your results. So, it's best to have your tests done the same way, and usually in the same lab. This allows your provider to compare your results over time. If you have questions about your results, talk with your provider. Learn more about laboratory tests, reference ranges, and understanding results .
Medicare NCD code list — diagnoses CMS lists as supporting medical necessity
Showing 18 of 195 diagnoses CMS lists as covered for this test under NCD 190.26. The complete list is in CMS's Lab NCD code list; a listing is CMS's published code list, not a coverage determination for any claim.
Clinical Protocol & Patient Advice
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If you smoke , you may need to stop for a while before your test. That's because smoking increases CEA levels. Depending on what type of test you're getting, your provider will let you know if there are any special instructions to follow. For a CEA blood test , you usually don't need to do anything to prepare. If your provider wants to collect peritoneal fluid (from your belly) or cerebrospinal fluid from your spine, they may ask you to empty your bladder (pee) and bowels (poop) before the test.
Usage Guidance
- Reference ranges vary by laboratory. Always discuss your specific results with a qualified healthcare professional.
Source: MedlinePlus, National Library of Medicine. View the original.
Read from: MedlinePlus (NLM); reference ranges only where NIDDK, NIH ODS or NCI states the value, linked per page — Curated from federal sources. All data sources · How to read the labels
Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 20, 2026 · All releases and sources