Sign in →

Test Code CA 125 Cancer Antigen 125 (CA 125), Serum

Reporting Name

Cancer Ag 125 (CA 125), S

Useful For

Evaluating patients' response to ovarian cancer therapy


Predicting recurrent ovarian cancer

Specimen Required

Patient Preparation: 12 hours before this blood test do not take multivitamins or dietary supplements containing biotin (vitamin B7) which are commonly found in hair, skin, and nail supplements and multivitamins.


Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 0.6 mL

Seattle Children's Hospital Note:

Collect 1.2 mL whole blood in Red top.

Specimen Type


Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Refrigerated (preferred) 5 days
  Frozen  180 days

Day(s) and Time(s) Performed

Monday through Friday; 5 a.m.-12 a.m.

Saturday; 6 a.m.-6 p.m.

Seattle Children's Hospital Note:

TAT: 3 - 5 days

Performing Laboratory

Mayo Medical Laboratories in Rochester

Method Name

Electrochemiluminescent Immunoassay

Method Description

The instrument used is the Roche Cobas 6000 e601. The Roche Elecsys CA 125 II (Cancer Antigen 125) method 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. This method has been standardized against the Enzymun-Test CA 125 II method which has been standardized against the CA 125 II RIA from Fujirebio Diagnostics, Inc.(Package insert: Roche CA 125 II reagent, USAV1.0. Roche Diagnostic Corp., Indianapolis, IN 2015-10)

Reference Values

Females: <46 U/mL

Males: Not applicable

Test Classification

This test has been cleared or approved by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
CA25 Cancer Ag 125 (CA 125), S 83082-8


Result ID Test Result Name Result LOINC Value
CA25 Cancer Ag 125 (CA 125), S 83082-8

Reject Due To


Mild OK; Gross OK


Mild OK; Gross OK