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Cancer antigen 125 (CA-125) is a protein found on the surface of many ovarian cancer cells. It also can be found in other cancers and in small amounts in normal tissue. A CA-125 test measures the amount of this protein in the blood.
CA-125 is used as a tumour marker, which means the test can help show if some types of cancer are present. Most often, the CA-125 test is used to check how well treatment for ovarian cancer is working or to see if ovarian cancer has returned.
The test for cancer antigen 125 (CA-125) is used to:
The CA-125 test is not recommended as a screening test for ovarian cancer at this time because it often has false-positive results. But the CA-125 test and an ultrasound scan may be used to test women who have a high chance of developing ovarian cancer. Women have a high risk of getting ovarian cancer if they have a family history of ovarian cancer or certain changes (mutations) in their DNA (BRCA1 or BRCA2).
You do not need to do anything before you have this test.
The health professional drawing blood will:
The elastic band around your upper arm may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.
There is very small chance of problems from having blood drawn from a vein.
The cancer antigen 125 (CA-125) test measures the amount of the CA-125 protein in the blood.
The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.
Less than 35 units per millilitre (U/mL)
Less than 35 kiloUnits per litre (kU/L) (SI units)
Results of a cancer antigen 125 test can be affected by:
CitationsFischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.Other Works ConsultedChernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.Pagana KD, Pagana TJ (2010). Mosby's Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby.
Current as of: April 29, 2020
Author: Healthwise StaffMedical Review: Kathleen Romito MD - Family MedicineThomas M. Bailey MD - Family MedicineJimmy Ruiz MD - Hematology, Oncology
Current as of: April 29, 2020
Author: Healthwise Staff
Medical Review:Kathleen Romito MD - Family Medicine & Thomas M. Bailey MD - Family Medicine & Jimmy Ruiz MD - Hematology, Oncology
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