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Clinical Test & Procedure Reference

CA 19-9 Blood Test (Pancreatic Cancer)

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.

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)

Why is this test ordered? 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.

Clinical Interpretation

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 .

Medicare NCD code list — diagnoses CMS lists as supporting medical necessity

C22.1Intrahepatic bile duct carcinomaMedicare medical-necessity (NCD 190.30)C23Malignant neoplasm of gallbladderMedicare medical-necessity (NCD 190.30)C24.0Malignant neoplasm of extrahepatic bile ductMedicare medical-necessity (NCD 190.30)C24.1Malignant neoplasm of ampulla of VaterMedicare medical-necessity (NCD 190.30)C24.8Malignant neoplasm of overlapping sites of biliary tractMedicare medical-necessity (NCD 190.30)C24.9Malignant neoplasm of biliary tract, unspecifiedMedicare medical-necessity (NCD 190.30)C25.0Malignant neoplasm of head of pancreasMedicare medical-necessity (NCD 190.30)C25.1Malignant neoplasm of body of pancreasMedicare medical-necessity (NCD 190.30)C25.2Malignant neoplasm of tail of pancreasMedicare medical-necessity (NCD 190.30)C25.3Malignant neoplasm of pancreatic ductMedicare medical-necessity (NCD 190.30)C25.4Malignant neoplasm of endocrine pancreasMedicare medical-necessity (NCD 190.30)C25.7Malignant neoplasm of other parts of pancreasMedicare medical-necessity (NCD 190.30)C25.8Malignant neoplasm of overlapping sites of pancreasMedicare medical-necessity (NCD 190.30)C25.9Malignant neoplasm of pancreas, unspecifiedMedicare medical-necessity (NCD 190.30)C78.7Secondary malignant neoplasm of liver and intrahepatic bile ductMedicare medical-necessity (NCD 190.30)C78.80Secondary malignant neoplasm of unspecified digestive organMedicare medical-necessity (NCD 190.30)C78.89Secondary malignant neoplasm of other digestive organsMedicare medical-necessity (NCD 190.30)D37.6Neoplasm of uncertain behavior of liver, gallbladder and bile ductsMedicare medical-necessity (NCD 190.30)

Showing 18 of 28 diagnoses CMS lists as covered for this test under NCD 190.30. 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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    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.

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 28, 2026 · All releases and sources