On this page:

• What is the CA125 blood test?
• What is a normal CA125 level?
• How do I get my test result?
• What if I have a high CA125 level?
• What if my symptoms continue?

What is the CA125 blood test?

CA125 is a protein that’s found in your blood. Ovarian cancer, as well as other conditions, can sometimes raise the level of CA125 in your blood.

During a CA125 blood test, a small sample of your blood will be taken and sent to a laboratory to measure the level of the CA125 protein. 

As well as helping to diagnose or rule out ovarian cancer, CA125 blood tests are sometimes used to monitor the treatment of ovarian cancer or check for signs of recurrence (the cancer returning).

For more information about the CA125 blood test, speak to one of our nurse advisers by contacting our support line on 0808 802 6000 (freephone) or speak to your GP.

When should I request a CA125 blood test?

If you have symptoms of ovarian cancer, you should ask your GP about having a CA125 blood test. The CA125 blood test is a useful way to gather some more information and will help your GP decide what to do next. 

The main symptoms of ovarian cancer are:  

• persistent bloating (pooing more or less often than normal)    
• feeling full quickly and/or loss of appetite  
• pain in your tummy or pelvis (the area between your hip bones)  
• needing to wee more urgently or more often than usual. 

Sometimes there can be other symptoms:

• diarrhoea or constipation (a change in your bowel habit)  
• fatigue (feeling very tired)  
• losing weight without trying  
• unusual vaginal bleeding before the menopause or any vaginal bleeding after the menopause. 

Contact your GP surgery if you have one or more of these symptoms and they don’t go away or happen frequently (such as more than 12 times a month or 3 times a week).  

Tell your GP if one or more relative in your close family has had cancer especially if the cancer affected your mother, father, brother or sister. This is because ovarian cancer can run in families.

How should I prepare for a CA125 blood test?

If your blood is only being tested for CA125, you can eat and drink normally before the test and resume your normal activity straight afterwards.

Your GP may suggest that you delay the test if you're on your period as it may affect the result.

What is a normal CA125 level?

Until recently, no matter how old you are, a CA125 level less than 35 units per millilitre (u/ml) was considered normal. A CA125 level over 35 u/ml meant you should be sent for more tests.

In April 2026 the National Institute for Health and Care Excellence (NICE) updated its guidance on CA125 levels depending on someone’s age. That’s because research has shown that the CA125 test is less accurate for detecting ovarian cancer in younger women and that different age groups tend to have different levels of CA125 in their blood. 

What our video below to learn more about the CA125 blood test and what the results might mean.
(This video was created before NICE updated the CA125 levels by age for England, Wales and Northern Ireland. Find out your age threshold below). 

If you live in England, Wales or Northern Ireland and your CA125 level is higher than the level set for your age group, your doctor should send you for further tests like an ultrasound scan.

This table shows the different CA125 levels for each age group:

If you’re 39 years old or younger, your GP should consider an urgent ultrasound scan. They may also recommend a CA125 blood test but they shouldn’t use it as the only test. 

If you live in Scotland, your doctor should send you for a CA125 blood test and ultrasound scan at the same time, no matter what age you are.