DefinitionBy Mayo Clinic staff
A CA 125 test measures the amount of the protein CA 125 (cancer antigen 125) in your blood.
Many different conditions can cause an increase in CA 125. These include uterine fibroids, endometriosis, pelvic inflammatory disease and cirrhosis, as well as pregnancy and normal menstruation. Certain cancers, including ovarian, endometrial, peritoneal and fallopian tube, also can cause CA 125 to be released into the bloodstream.
A CA 125 test isn't accurate enough to use for cancer screening in all women — especially premenopausal women — because many benign conditions can increase the CA 125 level. What's more, CA 125 levels are normal in many women with early-stage ovarian cancer.
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