The CA 19-9 blood test measures a protein called CA 19-9, which is found in your blood sample. CA 19-9 is a type of tumour marker. Tumour markers are substances produced by cancer cells in your body or by normal cells in response to cancer.
Healthy people may have small amounts of CA 19-9 in their blood. High levels of CA 19-9 can often be a sign of pancreatic cancer. But high levels can also be a sign of other types of cancer or some non-cancerous conditions.
For example, gallstones and liver cirrhosis can cause high CA 19-9 levels.
Because high CA 19-9 levels can mean different things, this test is not used alone to screen for or diagnose cancer or other diseases. But it can help you monitor your cancer and check the effectiveness of your treatment.
Other names: cancer antigen 19-9, carbohydrate antigen 19-9, CA 199 measurement, CA 19-9 radioimmunoassay (RIA)
What is CA 19-9 blood test used for?
CA 19-9 blood tests can be used for:
Monitoring certain types of cancer and cancer treatment: CA 19-9 levels usually rise as cancer grows and decrease as tumours shrink. Therefore, it can be used to assess the effectiveness of the treatment process.
Predicting how the cancer may behave over time: CA 19-9 levels can give clues about the progression of cancer and can be helpful in predicting the future course of the disease.
To check whether the cancer has returned after treatment: CA 19-9 levels can be monitored to determine whether the cancer has returned after treatment.
Diagnosing certain types of cancer and other diseases when used in combination with other tests: The CA 19-9 test can help diagnose certain types of cancer and other diseases when used in combination with other clinical findings and imaging methods.
Although some people have high levels of CA 19-9, this marker may not be produced: In this case, the CA 19-9 test may not be useful in diagnosing cancer.
Why is a CA 19-9 Test Needed?
Diagnosis of pancreatic cancer or another cancer that causes high CA 19-9 levels: If you have been diagnosed with pancreatic cancer or another cancer that raises CA 19-9 levels, your healthcare provider may order the CA 19-9 blood test.
Related cancers: Certain types of cancer, such as bile duct, colon and rectum, stomach, ovaries, or bladder, can affect CA 19-9 levels.
Monitoring the treatment process: During cancer treatment, your healthcare professional may order a CA 19-9 test regularly to check whether the treatment is effective.
Post-treatment check-up: After treatment is complete, CA 19-9 tests may be done to see if the cancer has returned. High levels of CA 19-9 can be a sign that the cancer has started to grow again.
What is the CA 19-9 Blood Test Normal Value and High Level?
The serum CA 19-9 level is a tumour marker examined in cases of suspected cancer in the gallbladder, pancreas, liver cells and gastrointestinal tract.
Moderately high values (above 1000) are usually suggestive of cancer. Increased CA 19-9 levels can be observed in pancreatitis and benign bile duct diseases.
What Do CA 19-9 Test Results Mean?
If your CA 19-9 levels are rising:
The tumour may be growing.
Your treatment may be ineffective.
Additional tests may be required to reach a definitive conclusion.
If your CA 19-9 levels are decreasing:
The tumour may be shrinking.
Your treatment may be effective.
If your CA 19-9 levels remain the same:
Your disease may be stable.
Your condition may have got neither better nor worse.
Your CA 19-9 levels dropped after treatment, but then increased:
The cancer may have returned or may have grown.
More tests may be needed to determine the true cause.
If you do not have cancer but your CA 19-9 test results are high, you may not have a health problem that needs treatment. Healthy people may have high levels of CA 19-9.
However, high levels can be a sign of conditions such as
Pancreatitis: Inflammation of the pancreas.
Gallstones: Stones that form in the gallbladder or bile ducts.
Bile duct disease: Diseases that affect the bile ducts, including conditions such as blockage or infection.
Liver disease: Various diseases that occur in the liver.
Cystic fibrosis: Cystic fibrosis, an inherited disease.
Talk to your healthcare professional about what your results mean. If your healthcare professional thinks you may have one of these conditions, you will probably need further tests for a definitive diagnosis.
Is there anything else to know about the CA 19-9 test?
Laboratories use different methods to measure the amount of CA 19-9 in your blood sample. The test method may affect your results. If you have regular tests to monitor cancer, it is important that your tests are done in the same way and usually at the same lab.
This allows your provider to compare your results over time. Your test report usually tells you which method was used to measure your CA 19-9 levels. If you have any questions about how your tests were done, talk to your provider.
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