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HelpTEST ID CA25 Cancer Antigen 125 (CA 125), Serum
Reporting Name
Cancer Ag 125 (CA 125), SUseful For
Evaluating individuals' response to ovarian cancer therapy
Predicting recurrent ovarian cancer
This test is not useful for cancer detection screening in the normal population.
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
SerumSpecimen Required
Patient Preparation: For 12 hours before specimen collection, patient should not take multivitamins or dietary supplements (eg, hair, skin, and nail supplements) containing biotin (vitamin B7).
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Specimen Minimum Volume
0.75 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum | Refrigerated (preferred) | 5 days |
| Frozen | 168 days |
Reference Values
Males: Not applicable
Females: <46 U/mL
Day(s) Performed
Monday through Friday
CPT Code Information
86304
Clinical Information
Cancer antigen 125 (CA 125) is a glycoprotein antigen normally expressed in tissues derived from coelomic epithelia (ovary, fallopian tube, peritoneum, pleura, pericardium, colon, kidney, stomach).
Serum CA 125 is elevated in approximately 80% of women with advanced epithelial ovarian cancer, but the assay sensitivity is suboptimal in early disease stages. The average reported sensitivities are 50% for stage I and 90% for stage II or greater.
Elevated serum CA 125 levels have been reported in individuals with a variety of nonovarian malignancies including cervical, liver, pancreatic, lung, colon, stomach, biliary tract, uterine, fallopian tube, breast, and endometrial carcinomas.
Elevated serum CA 125 levels have been reported in individuals with a variety of benign conditions including: cirrhosis, hepatitis, endometriosis, first trimester pregnancy, ovarian cysts, and pelvic inflammatory disease. Elevated levels during the menstrual cycle also have been reported.
Cautions
Results cannot be interpreted as absolute evidence of the presence or absence of disease.
Serum markers are not specific for malignancy and values may vary by method. Values obtained with different assay methods cannot be used interchangeably.
Some individuals have antibodies to mouse protein (HAMA), which can cause interference in immunoassays that employ mouse antibodies. In particular, it has been reported that serum specimens from patients who have undergone therapeutic or diagnostic procedures that include infusion of mouse monoclonal antibodies may produce erroneous results in such assays. Rerunning the specimen in question after additional blocking treatment may resolve the issue.
No interference was observed from rheumatoid factors up to a concentration of 1200 IU/mL.
There is no high-dose hook effect at cancer antigen 125 concentrations of up to 50,000 U/mL.
Method Description
The Roche Elecsys CA 125 II (cancer antigen 125) assay is a sandwich electrochemiluminescence immunoassay that employs a biotinylated monoclonal CA 125-specific antibody and a monoclonal CA 125-specific antibody labeled with a ruthenium complex. CA 125 in the specimen reacts with both the biotinylated monoclonal CA 125-specific antibody (mouse) and the monoclonal CA 125-specific antibody (mouse) labeled with ruthenium, forming a sandwich complex. Streptavidin-coated microparticles are added and the mixture is aspirated into the measuring cell where the microparticles are magnetically captured onto the surface of the electrode. Unbound substances are then removed with ProCell. Application of voltage to the electrode induces the chemiluminescent emission, which is then measured against a calibration curve to determine the amount of CA 125 in the patient specimen.(Package insert: Elecsys CA 125 II. Roche Diagnostics; V2.0, 07/2024)
Report Available
1 to 3 daysSpecimen Retention Time
14 daysReject Due To
| Gross hemolysis | OK |
| Gross lipemia | OK |
Method Name
Electrochemiluminescent Immunoassay (ECLIA)
Forms
If not ordering electronically, complete, print, and send an Oncology Test Request (T729) with the specimen.