Clinics and Departments

Laboratory Services

Lab Dept:


Test Name:


General Information

Lab Order Codes:



CA 125; Carbohydrate Antigen 125; Ovarian Cancer-Related Antibodies

CPT Codes:

86304 – CA 125

Test Includes:

CA 125 level measured in U/mL.


Test Indications:

Useful for evaluating patients’ response to cancer therapy, especially for ovarian carcinoma. Predicting recurrent ovarian cancer or intraperitoneal tumor.

Lab Testing Sections:

Chemistry – Sendouts

Referred to:

Mayo Medical Laboratories (MML Test: 9289/CA25)

Phone Numbers:

MIN Lab: 612-813-6280

STP Lab: 651-220-6550

Test Availability:

Daily, 24 hours

Turnaround Time:

1-3 days, test performed Monday - Saturday

Special Instructions:



Specimen Type:



Red top tube

Draw Volume:

1.8 mL (Minimum: 1.5 mL) blood

Processed Volume:

0.6 mL (Minimum: 0.5 mL) serum


Routine venipuncture

Special Processing:

Lab Staff: Centrifuge specimen, remove serum aliquot into a screw-capped, round bottom plastic vial. Store and ship at refrigerated temperatures.

Patient Preparation:


Sample Rejection:

Mislabeled or unlabeled specimens; gross hemolysis


Reference Range:

<35 U/mL

Interpretation: In monitoring studies, elevated levels of cancer antigen 125 (CA 125) (>35 U/mL) are a predictor of the presence of intraperitoneal tumor or recurrence. Elevated concentrations have been found in about 72% of patients with surgically proven recurrent ovarian carcinoma. However, normal levels do not rule out recurrence.

A persistently rising CA 125 value suggests progressive malignant disease and poor therapeutic response. Physiologic half-life of CA 125 is approximately 5 days.

In patients with advanced disease who have undergone cytoreductive surgery and are on chemotherapy, a prolonged half-life (>20 days) may be associated with a shortened disease-free survival.

Critical Values:



Not useful as a screening assay for cancer detection in the normal population. Results cannot be interpreted as absolute evidence of the presence or absence of disease. Serum markers are not specific for malignancy and values 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 samples 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.


Immunoenzymatic Assay


Mayo Medical Laboratory July 2013


5/11/2010: Volume update.
6/16/2010: Shipping temp changed from frozen to refrigerated. Frozen will still be accepted, refrigerated is preferred.

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