Blood test

Normal CA 19-9 (Carbohydrate antigen) in a blood test

Blood test
Normal CA 19-9 (Carbohydrate antigen) in a blood test
Last update: 17/06/2021

What is the normal value of CA 19-9 (Carbohydrate antigen) in a blood test?

The normal range of the CA 19-9 (Carbohydrate Antigen) is expressed in kU/ml.

Men: < 37 kU/l
Women: < 37 kU/l
Children: < 37 kU/l

Why normal levels can differ across different labs?

Each laboratory must establish its own normal range for the CA 19-9 (Carbohydrate Antigen) in a blood test. These ranges depend on the makeup of the local population, the technologies used and the accuracy of the measurement. There may be also slight differences in the normal levels according to age, gender, race or ethnic origin, geographic region, diet, type of sample and other relevant status.

Your doctor will study the results along with your medical record, screenings, physical condition, symptoms and any other relevant information about your situation.

If the CA 19-9 test must be performed periodically to monitor the treatment of a cancer, such as pancreatic cancer, it is recommended to perform the tests always in the same laboratory in order to properly compare the results avoiding interferences by the methods or procedures used by different labs.

What does CA 19-9 (Carbohydrate antigen) mean?

CA 19-9 (Carbohydrate antigen) is a high molecular mass (200 to 1000 kDa) glycoprotein complex present in the blood as a mucin.

CA 19-9 is synthesized by normal human pancreatic and biliary ductular cells and by gastric, colon, endometrial, and salivary epithelia.

It is a protein found elevated in the blood of patients diagnosed with gastrointestinal tumors.

What is the CA 19-9 (Carbohydrate antigen) test used for?

The CA 19-9 (Carbohydrate antigen) is a tumor marker. It means that it raises in the presence of a malignant tumor. It is used to help evaluate the outcome of therapy for malignancies of the pancreas, colorectal or biliary tract.

The CA 19-9 test is useful in the following clinical applications:

  • It is an antigen helpful in post-therapeutic monitoring of a cancer to determine the success of therapy or the presence of cancer recurrence.
  • For monitoring gastrointestinal cancers, head and neck tumors, and gynecologic tumors. It is frequently used in monitoring patients diagnosed with pancreatic cancer.
  • Predicts the recurrence of stomach, pancreatic, liver, and colorectal malignancies.
  • Used in combination with other tumor markers it is helpful for earlier detection of recurrence and development of metastases.

In case of metastasis, values may be higher than 1000 KU/l.

Where can I find more information about CA 19-9 (Carbohydrate antigen) in a blood test?

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Which values are considered a normal CA 19-9 (Carbohydrate antigen) in a blood test?

The following values are considered to be normal values:

IMPORTANT: These levels are expressed in kU/l. They are an example of a healthy non-smoker man/woman of about 40 years old with no known disease and not taking any medication. The ranges can be different depending on the laboratory or on your personal circumstances.

CA 19-9
0 kU/l1 kU/l2 kU/l3 kU/l4 kU/l5 kU/l6 kU/l7 kU/l
8 kU/l9 kU/l10 kU/l11 kU/l12 kU/l13 kU/l14 kU/l15 kU/l
16 kU/l17 kU/l18 kU/l19 kU/l20 kU/l21 kU/l22 kU/l23 kU/l
24 kU/l25 kU/l26 kU/l27 kU/l28 kU/l29 kU/l30 kU/l31 kU/l
32 kU/l33 kU/l34 kU/l35 kU/l36 kU/l37 kU/l  
Medically reviewed by our Medical staff on 17/06/2021


  • Concise Book of Medical Laboratory Technology: Methods and Interpretations. 2nd Edition. 2015. Ramnik Sood. ISBN: 978-93-5152-333-8. Pag. 683.
  • Laboratory tests and diagnostic procedures: with nursing diagnoses. Jane Vincent Corbett, Angela Denise Banks. 8th ed. 2013. ISBN: 978-0-13-237332-6. Pag. 250.
  • Tietz. Fundamentals of Clinical Chemistry. Carl A. Burtis, Edward R. Ashwood, David e. Bruns. 6th edition. 2008. Pag 355. ISBN: 978-0-7216-3865-2.

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