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Cancer Antigen 125 (CA 125)

Test Codes

EPIC: LAB5803, Beaker: CA125, Antrim: 30220

Department

Chemistry

Specimen Collection Criteria

Collect: One Gold-top SST tube. (Minimum Whole Blood: 2.0 mL)

Physician Office/Draw Specimen Preparation

Preparation for Courier Transport

Transport: Centrifuged collection tube, refrigerated (2-8°C or 36-46°F). (Minimum Serum: 0.5 mL)

Rejection Criteria

Plasma specimens.

Severely lipemic, icteric, or hemolyzed specimens.

In-Lab Processing

Let specimen clot 30-60 minutes then immediately centrifuge to separate serum from cells. Room temperature is acceptable for a maximum of 2 hours. Serum must be frozen (-20°C/-4°F or below) if not tested within 24 hours of collection. (Minimum Serum: 0.5 mL)

Storage

Specimen Stability for Testing:

Centrifuged SST Tubes and Microtainers^® with Separator Gels
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable

Red-top Tubes and Microtainers^® without Separator Gels
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): Unacceptable
Frozen (-20°C/-4°F or below): Unacceptable

Serum Specimens (Pour-Overs)
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 2 months

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days

Laboratory

Dearborn Chemistry Laboratory
Royal Oak Automated Chemistry Laboratory

Performed

Monday – Friday.
Results available in 2 business days.

Reference Range

Less than or equal to 35 U/mL.

Test Methodology

Chemiluminescent Immunoassay.

Interpretation

Individuals receiving mouse immunoglobulin by parenteral routes may produce anti-mouse antibodies. Serum from such individuals may produce erroneous results. CA-125 assay should not be performed until at least three weeks after the completion of primary chemotherapy and at least two months after abdominal surgery as these procedures may affect the assay.

Half Life in Blood: 4.8 days.

Clinical Utility

Conditions that cause elevated CA 125 levels include: ovarian cancer, pregnancy, ovarian cysts, uterine leiomyomas, pelvic inflammatory disease, endometriosis and menstruation.

CA 125 is the most important tumor marker for the management of ovarian cancer. It is best used as an adjunct test with ultrasound or in combination with a second tumor marker test. Predictive values approach 100%, when it is added to other diagnostic tests in postmenopausal women. However, because of its lack of specificity, CA 125 is NOT recommended as a general screen for ovarian cancer.

Serial CA 125 measurements after surgical debulking and chemotherapy are useful as a prognostic indicator, and the rate of fall of CA 125 levels has a positive correlation with five year survival. Rising CA 125 level post-treatment can often occur before radiological evidence of recurrent disease by as much as 12 months (1).

Reference

1. Orum DH, Jeyarajah AR. The role of ultrasound and tumor markers in the early detection of ovarian cancer. Bri J Obste Gynecol 1994; 101: 939-945.

CPT Codes

86304
LOINC: 10334-1

Contacts

Last Updated

10/3/2023