CA-125 is a protein shed by cells that line parts of the abdomen, chest and reproductive organs. Laboratories measure the amount that reaches the bloodstream. You may have this test to help look into pelvic symptoms or a finding on a scan. In some situations a doctor uses it to follow a known condition over time.

What is a normal CA-125 test range?

A typical adult range is around Often quoted against a figure of about 35 U/mL, but this is only a guide; many benign conditions raise it, so a value is read in context [ACOG, 2016]. No India-specific national reference interval is published for this parameter; your lab's printed range is the most reliable comparison. Ranges vary by lab, method and equipment — the range printed on your own report is the one that applies to your result.

CA-125 — What It Means in Your Blood Test

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Tumour marker results are complex. This page explains what the test measures — your doctor or specialist interprets your result in full clinical context, alongside your history and other tests.

What CA-125 cannot tell you

CA-125 is not a test for ovarian cancer. Many common, non-cancer conditions raise it, particularly before menopause. A high CA-125 does not mean cancer, and a normal one does not rule it out. Your doctor reads it with a scan and your history [ACOG, 2016].

This is a protein that the lining of some body cavities and the ovaries can release into the blood.

Many everyday, harmless conditions raise CA-125, especially before menopause. A doctor never reads it alone, but alongside a scan, your symptoms and your history.

Also known as: Cancer antigen 125, CA125, Carbohydrate antigen 125, MUC16

Best within range, not higher or lower

This isn't a case where higher or lower is better. Your body keeps it in a narrow band, and both directions can matter.

Last reviewed: 2026-08-16

What does CA-125 do in your body?

CA-125 helps a doctor follow what is happening in the pelvis and abdomen, most often around the ovaries. Because periods, fibroids and other common conditions lift it, it means most when tracked over time and read with a scan [ACOG, 2016].

What is CA-125?

CA-125 is a protein shed by cells that line parts of the abdomen, chest and reproductive organs. Laboratories measure the amount that reaches the bloodstream.

Why is CA-125 tested?

You may have this test to help look into pelvic symptoms or a finding on a scan. In some situations a doctor uses it to follow a known condition over time.

What can raise CA-125

Common, non-cancer causes

Menstruation — the level is often higher around the time of a period [ACOG, 2016]
Endometriosis [ACOG, 2016]
Uterine fibroids [ACOG, 2016]
Pelvic inflammatory disease or another pelvic infection [ACOG, 2016]
Pregnancy, especially in the first three months [ACOG, 2016]
Benign ovarian cysts [ACOG, 2016]

Causes a doctor will also consider

Ovarian cancer, which a doctor investigates with a scan and a specialist assessment when the wider picture warrants it [ACOG, 2016]
Other cancers and conditions affecting the abdomen or chest lining, which a doctor considers in context [NACB, 2008]

A single CA-125 is hard to read, especially before menopause. Doctors watch how it changes over time and read it with a scan, an examination and your history [ACOG, 2016].

What is a normal CA-125 range?

India: No India-specific national reference interval is published for this parameter; your lab's printed range is the most reliable comparison.
Global: Often quoted against a figure of about 35 U/mL, but this is only a guide; many benign conditions raise it, so a value is read in context [ACOG, 2016]

Ranges vary by lab, method and equipment — the range printed on your own report is the one that applies to your result.

Source: [ACOG, 2016]

What does your CA-125 value mean?

There is no widely-accepted set of value bands for this parameter. Compare your result with the reference range printed on your own report, and discuss it with your doctor.

What does a high CA-125 result mean?

A raised CA-125 most often reflects a benign cause, particularly before menopause. Your doctor weighs these first, alongside a scan and your symptoms, before any next step.

What does a low CA-125 result mean?

A within-range CA-125 is reassuring but not a guarantee, as some ovarian conditions do not raise it. It is read with a scan, an examination and your history.

What can affect your CA-125 result?

Where you are in your menstrual cycle
Being before or after menopause
Endometriosis, fibroids or pelvic infection
Pregnancy
The laboratory method used

Questions to ask your doctor

About this result

Read with my scan and where I am in my cycle, how should we interpret my CA-125?
Could endometriosis, fibroids or a recent infection be lifting my CA-125?

What to do next

Do my CA-125 and scan together suggest watching, or seeing a specialist?

About retesting

Would repeating CA-125 at a different point in my cycle give a clearer picture?

Frequently asked questions

What is CA-125?: CA-125 is a protein shed by cells that line parts of the abdomen, chest and reproductive organs. Laboratories measure the amount that reaches the bloodstream. You may have this test to help look into pelvic symptoms or a finding on a scan. In some situations a doctor uses it to follow a known condition over time.
What is a normal CA-125 test range?: A typical adult range is around Often quoted against a figure of about 35 U/mL, but this is only a guide; many benign conditions raise it, so a value is read in context [ACOG, 2016]. No India-specific national reference interval is published for this parameter; your lab's printed range is the most reliable comparison. Ranges vary by lab, method and equipment — the range printed on your own report is the one that applies to your result.
What does a high CA-125 result mean?: A raised CA-125 most often reflects a benign cause, particularly before menopause. Your doctor weighs these first, alongside a scan and your symptoms, before any next step.
What does a low CA-125 result mean?: A within-range CA-125 is reassuring but not a guarantee, as some ovarian conditions do not raise it. It is read with a scan, an examination and your history.
What can affect your CA-125 result?: Several everyday factors can influence it, including Where you are in your menstrual cycle, Being before or after menopause, Endometriosis, fibroids or pelvic infection, Pregnancy, The laboratory method used.

Sources

ACOG (2016) — ACOG Practice Bulletin No. 174: Evaluation and Management of Adnexal Masses
NACB (2008) — National Academy of Clinical Biochemistry: Use of Tumor Markers in Clinical Practice
NACB (2008) — National Academy of Clinical Biochemistry: Use of Tumor Markers in Clinical Practice

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