CA 19-9 Blood Test (Pancreatic Cancer): MedlinePlus Medical Test

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You Are Here: Home → Medical Tests → CA 19-9 Blood Test (Pancreatic Cancer) URL of this page: https://medlineplus.gov/lab-tests/ca-19-9-blood-test-pancreatic-cancer/ CA 19-9 Blood Test (Pancreatic Cancer)

What is a CA 19-9 blood test?

A CA 19-9 test measures the amount of a protein called CA 19-9 (cancer antigen 19-9) in a sample of your blood. CA 19-9 is a type of tumor marker. Tumor markers are substances made by cancer cells or by normal cells in response to cancer.

High levels of CA 19-9 can be a sign of certain cancers of the digestive tract. These include cancers of the:

• Pancreas.
• Bile duct.
• Colon and rectum.
• Stomach.
• Ovaries.
• Bladder.

However, high CA 19-9 levels can also be a sign of other conditions, including:

• Gallstones, which can block your bile ducts.
• Cholangitis, which is an infection of the bile ducts.
• Pancreatitis, which is inflammation of the pancreas.
• Cirrhosis (or scarring) of the liver.
• Bile duct disease, including a blockage or infection.
• Liver disease.
• Cystic fibrosis.

Because high levels of CA 19-9 can mean different things, health care providers don't use the results from a CA 19-9 test alone to screen for or diagnose cancer or other diseases. To do this, your provider will have to consider the results of a CA19-9 test as well as the results of other tests.

Other names: cancer antigen 19-9, carbohydrate antigen 19-9, CA 19-9 measurement, CA 19-9 radioimmunoassay (RIA)

What is it used for?

CA 19-9 blood tests may be used to:

• Monitor certain types of cancer and cancer treatment. CA 19-9 levels often go up as cancer grows and go down as tumors shrink. So, your provider may order this test throughout your treatment to see how well it's working.
• Help make a prognosis. A prognosis is a health care professional's prediction for how an illness will behave over time. Your provider may use this test to help determine your cancer's stage (how advanced it is) and how likely it is to respond to treatment.
• Check whether cancer has returned after treatment. Because high CA 19-9 levels will often show up before you get any other symptoms of cancer, your provider may use this test along with several others to see if your cancer has returned.
• Check for the presence of certain cancers, but only when used with other tests.

Some people do not make CA 19-9 even when they have a cancer that usually produces high levels of CA 19-9. For these people, a CA 19-9 test is not useful.

If your provider is using a CA 19-9 blood test to help check for signs of cancer, they will perform additional tests, including:

• A physical examination. Some cancers associated with CA 19-9 can have noticeable symptoms. For example, pancreatic cancer can cause your liver or gallbladder to swell.
• Imaging tests, such as x-rays, computer tomography (CT) scans, and magnetic resonance imaging (MRI).
• Cholangiopancreatography. Your provider can use this to look at the pancreatic ducts and bile ducts to see if they're blocked or narrowed. If they are, it could be a sign of a pancreatic tumor.

Why do I need a CA 19-9 test?

You may need a CA 19-9 blood test if you:

• Have been diagnosed with any of the types of cancer associated with CA 19-9.
• Are going through cancer treatment. Your provider may test you on a regular basis to see if your treatment is working.
• Have completed cancer treatment. Your provider may test you to see if your CA 19-9 levels stay low. If they rise, it could be a sign that your cancer has returned.

Your provider may also order this test if you have symptoms of the cancers associated with high CA 19-9 levels. These can include:

• Jaundice (yellowing of the skin).
• Weight loss.
• Abdominal (belly) pain.
• Weakness.
• Swollen gallbladder or liver.

What happens during a CA 19-9 blood test?

A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

Will I need to do anything to prepare for the test?

Usually, you don't need any special preparations for a CA 19-9 blood test. But ask your provider to be sure. If you take certain vitamins, you may need to stop them before the test.

Are there any risks to the test?

There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

What do the results mean?

If you're being treated for cancer, you may be tested several times during your treatment. Your provider will look at all your test results to see how your CA 19-9 levels have changed. Your results may show:

• Your levels of CA 19-9 are increasing. This may mean your tumor is growing, and/or your treatment is not working. More tests are usually needed to find out for sure.
• Your levels of CA 19-9 are decreasing. This may mean your tumor is shrinking and your treatment is working.
• Your levels of CA 19-9 have stayed the same. This may mean your disease is stable and hasn't gotten better or worse.
• Your CA 19-9 levels decreased after treatment but increased later. This may mean your cancer has come back or grown. You'll need more tests to check whether cancer is really causing the higher level of CA 19-9.

If you don't have cancer but your test results show a high level of CA 19-9, you may not have a health problem that needs treatment. Healthy people can have high CA 19-9 levels. But high levels may be a sign of a condition, such as pancreatitis or gallstones.

Talk with your provider about what your results may mean.

If your provider thinks you may have one of these conditions, you will probably need other tests to find out for sure.

Learn more about laboratory tests, reference ranges, and understanding results.

Is there anything else I need to know about a CA 19-9 test?

Labs use different methods to measure the amount of CA 19-9 in your blood sample. The test method can affect your results. If you're having regular tests to monitor cancer, it's important to have your tests done the same way, and usually in the same lab. This allows your provider to compare your results over time. Your test report usually says what method was used to measure your CA 19-9 levels. If you have any questions about how your tests are done, talk with your provider.

References

1. Allina Health [Internet]. Minneapolis: Allina Health; Cancer antigen 19-9 Measurement; [reviewed 2018 Jul 4; cited 2025 Sep 29]; [about 3 screens]. Available from: https://account.allinahealth.org/library/content/49/150320
2. American Cancer Society [Internet]. Atlanta: American Cancer Society Inc.; c2025. Pancreatic Cancer Stages; [updated 2024 Feb 5; cited 2025 Sep 29]; [about 9 screens]. Available from: https://www.cancer.org/cancer/pancreatic-cancer/detection-diagnosis-staging/staging.html
3. American Cancer Society [Internet]. American Cancer Society Inc.; 2025. Tests for Pancreatic Cancer; [updated 2024 Feb 5; cited 2025 Sep 29]; [about 8 screens]. Available from: https://www.cancer.net/cancer-types/pancreatic-cancer/diagnosis
4. Cleveland Clinic: Health Library: Diagnostics & Testing [Internet]. Cleveland (OH): Cleveland Clinic; 2025. Blood Tests; [reviewed 2022 Dec 06; cited 2025 Sep 29]; [about 16 screens]. Available from: https://my.clevelandclinic.org/health/diagnostics/24508-blood-tests
5. Johns Hopkins Medicine [Internet]. The Johns Hopkins University, The Johns Hopkins Hospital, and Johns Hopkins Health System; c2025. Pancreatic Cancer Diagnosis; [cited 2025 Sep 29]; [about 3 screens]. Available from: https://www.hopkinsmedicine.org/health/conditions-and-diseases/pancreatic-cancer/pancreatic-cancer-diagnosis
6. LabCorp [Internet]. Burlington (NC): Laboratory Corporation of America(r) Holdings; c2025. Patient Test Information: Carbohydrate Antigen (CA) 19-9; [cited 2025 Sep 29]; [about 7 screens]. Available from: https://www.labcorp.com/tests/002261/carbohydrate-antigen-ca-19-9
7. Lee SP, Sung IK, Kim JH, Lee SY, Park HS, Shim CS. Usefulness of Carbohydrate Antigen 19-9 Test in Healthy People and Necessity of Medical Follow-up in Individuals with Elevated Carbohydrate Antigen 19-9 Level. Korean J Fam Med. 2019 Sep [cited 2025 Sep 29];40(5):314-322. doi: 10.4082/kjfm.18.0057. Epub 2019 Apr 8. PMID: 30959581; PMCID: PMC6768838. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC6768838/
8. Mayo Clinic: Mayo Medical Laboratories [Internet]. Mayo Foundation for Medical Education and Research; c1995-2025. Test ID: CA19: Carbohydrate Antigen 19-9 (CA 19-9), Serum: Clinical and Interpretive; [cited 2025 Sep 29]; [about 2 screens]. Available from: https://www.mayocliniclabs.com/test-catalog/overview/9288#Clinical-and-Interpretive
9. National Cancer Institute [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; NCI Dictionary of Cancer Terms: CA 19-9; [cited 2025 Sep 29]; [about 1 screen]. Available from: https://www.cancer.gov/publications/dictionaries/cancer-terms/def/ca-19-9
10. National Cancer Institute [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; Tumor Markers; [reviewed 2023 Dec 7; cited 2025 Sep 29]; [about 4 screens]. Available from: https://www.cancer.gov/about-cancer/diagnosis-staging/diagnosis/tumor-markers-fact-sheet
11. Nemours KidsHealth [Internet]. Jacksonville (FL): The Nemours Foundation; c1995-2025. Getting a Blood Test; [reviewed 2021 Sep; cited 2025 Sep 29]; [about 4 screens]. Available from: https://kidshealth.org/en/parents/blood-tests.html
12. Pancreatic Cancer Action Network [Internet]. Manhattan Beach (CA): Pancreatic Action Network; c2025. CA 19-9 Blood Test for Pancreatic Cancer; [cited 2025 Sep 29]; [about 10 screens]. Available from: https://pancan.org/facing-pancreatic-cancer/diagnosis/ca19-9/
13. Puckett Y, Garfield K. TITLE. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. [Updated 2024 Sep 10; cited 2025 Sep 29]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK518996/
14. Testing.com [Internet]. Seattle (WA): OneCare Media; c2025. CA19-9 Blood Test (Cancer Antigen); [modified 2021 Nov 9; cited 2025 Sep 29]; [about 14 screens]. Available from: https://www.testing.com/tests/cancer-antigen-19-9/

Related Health Topics

• Bile Duct Cancer
• Cancer
• Cirrhosis
• Colorectal Cancer
• Gallstones
• Pancreatic Cancer
• Stomach Cancer

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The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health.

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