CA-125 Tumor Marker (Serum) with CA-19-9 Ratio
This test measures two cancer-related proteins—CA-125 and CA-19-9—in your blood to help assess certain types of cancer risk or progression.
["This ratio can help doctors track cancer growth or response to treatment in conditions like ovarian or pancreatic cancer."]
Key facts at a glance
- LOINC
- 68923-2
- Short code
- CA125PCF
- Synonyms
- Cancer Ag125 Pcar-aCnc
- Category
- chemistry
- Sample
- serum
- Container
- Sterile, leak-proof container (red-top or SST tube acceptable for transport); avoid heparin contamination when possible
- Units
- N/A
- Critical range
- 0.5 N/A – —
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–99 years
- Method
- Immunoassay (Electrochemiluminescence Immunoassay - ECLIA or Chemiluminescent Immunoassay - CLIA)
- CPT
- 86304
- SNOMED
- 104686009
- Specimen volume
- 1-2 mL of pericardial fluid
- Stability
- Stable for 24 hours at room temperature; 7 days at 2-8°C; 3 months at -20°C. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 30
- TAT
- 24–72 hours
- Order
- routine
Why This Test Is Done
Your doctor may order this test if you have symptoms of cancer, such as abdominal pain, bloating, or unexplained weight loss, or if you’re at higher risk due to family history or prior cancer diagnosis. It can also be used during follow-up for known cancers to monitor changes over time.
What to Expect Before the Test
No special preparation is needed, but you may be asked to fast for 8–12 hours before the blood draw if your lab uses a fasting protocol for CA-19-9 alone. Bring your recent test results to your appointment.
How the Test Works
Blood is drawn from a vein in your arm. The lab separates the serum (liquid part of blood without clots) and measures the levels of CA-125 and CA-19-9 proteins using immunoassay techniques. The ratio compares these two markers to identify patterns that may indicate cancer activity.
What the Results Mean
Results are not given as a single number but as a ratio. Elevated ratios may suggest conditions like ovarian cancer, pancreatic cancer, or other tumors that produce these proteins. Your doctor will interpret results in the context of your medical history and symptoms.
Reference range
No established reference range for pericardial fluid. Interpretation is clinical and based on comparison with serum CA 125 levels and pericardial fluid-to-serum ratio. Elevated pericardial fluid CA 125 may be associated with malignant pericardial effusion, particularly from ovarian, endometrial, or other epithelial malignancies.N/A
No special patient preparation required for pericardial fluid sampling. Pericardial fluid is obtained via pericardiocentesis performed by a qualified physician under imaging guidance.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
CA-125/CA-19-9 Ratio Test
Frequently asked questions
What does CA-125 stand for?
What does CA-19-9 stand for?
Why is a ratio used instead of individual levels?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 17, 2026. · Read our editorial policy