What is a normal CA125 level?
There’s no one normal number. With lasting symptoms, NICE advises a scan from 35 at 40 to 49, but from 24 at 60 to 69. Your period can push CA125 up 2 to 3 times.
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What is a normal CA125 level?
There’s no one normal number. Liverpool’s NHS lab prints a range of below 35. But NICE chose not to call below 35 normal.
Instead, NICE sets a line for an urgent scan. It’s for people with ovaries, aged 40 or over, with lasting symptoms. And the line changes with age.
| Age | Urgent scan if CA125 is |
|---|---|
| 40 to 49 | 35 or more |
| 50 to 59 | 31 or more |
| 60 to 69 | 24 or more |
| 70 to 79 | 25 or more |
| 80 and over | 31 or more |
Source: NICE NG12
Take a result of 30. At 45, it’s under the line. At 65, it’s over it, so NICE advises an urgent scan of your tummy and pelvis.
Think of the line like an airport scanner. A beep means a closer look. It doesn’t mean you’ve done anything wrong, and a raised CA125 doesn’t mean you have cancer.
Your report may say kU/L or U/mL. The lab says they’re the same. Ask your GP which age line they used for your result.
What is a CA125 blood test for?
CA125 (cancer antigen 125) is a protein that’s sometimes linked to ovarian cancer. A GP uses it to decide who needs a scan.
NICE says to test if these happen often, particularly more than 12 times a month, especially at 50 or over:
- a swollen or bloated tummy
- feeling full quickly, or losing your appetite
- pain in your tummy or pelvis
- needing to pee urgently or more often
What usually happens after a CA125 test
- 1
Blood test
CA125, if you’re 40 or over with lasting symptoms.
- 2
Scan
An urgent scan if your result is at or above the line for your age.
- 3
Specialist
A fast referral if the scan suggests cancer, usually within 2 weeks. This doesn’t definitely mean you have cancer.
- 4
Other causes
If the test or scan is clear, your GP looks for other causes.
Aged 50 or over with new symptoms like IBS (irritable bowel syndrome, which causes tummy cramps, bloating, diarrhoea or constipation) in the last year? NICE says to test, as IBS rarely starts at this age.
Under 40? NICE says not to rely on CA125 alone, as it isn’t accurate at this age. Your GP may offer an urgent scan instead.
Write down how often each symptom happens before you see your GP. More on bloating in blood tests for bloating.
Can CA125 be high without cancer?
Yes. Liverpool’s NHS lab says a raised CA125 may be found in 1 to 2 in 100 healthy people. Many other things can push it up too.
| Cause | What it can do to CA125 |
|---|---|
| Your period | May push it up 2 to 3 times |
| Endometriosis (womb-like tissue growing outside the womb) | May raise it a little |
| Pregnancy, first 6 months | May raise it a little |
| A pelvic infection, or fibroids (lumps in the womb that aren’t cancer) | May make it high |
| Liver scarring (cirrhosis) or a suddenly inflamed pancreas | May make it high |
| Fluid in the tummy (ascites) not caused by cancer | May raise it a lot |
That top line is why the lab says not to take blood during your period. These other causes can muddy results more before the menopause.
Got an ovarian cyst? Most aren’t cancer.
A doctor may check CA125 if there’s any concern a cyst could be cancer. After the menopause, regular scans and blood tests over a year are usually advised to keep an eye on a cyst.
Book your test for a day you’re not on your period.
Does a normal CA125 rule out ovarian cancer?
No. Early ovarian cancer often doesn’t raise it.
Source: Liverpool University Hospitals
A scan can miss things too. The NHS says ovaries are sometimes too small to show up, especially after the menopause.
So if your result is under the line, your GP should look for other causes. If none is found, NICE says to go back if symptoms come more often or don’t go away.
Six steps for a CA125 test
- Book your blood test for a day you’re not on your period.
- Write down how many times a month each symptom happens.
- Tell your GP if anyone in your family has or had ovarian or breast cancer.
- Tell your GP if you’re pregnant or have endometriosis.
- Ask for your CA125 number and the scan line for your age.
- Go back to your GP if symptoms don’t go away, get worse or come more often.
Sources: NHS; NICE NG12; Liverpool University Hospitals
Is there a blood test to screen for ovarian cancer?
No. There’s no national screening programme for ovarian cancer in the UK.
A large UK trial called UKCTOCS tested CA125 in women without symptoms. It found cancers earlier, but this didn’t save lives.
At high risk because of your genes? If you don’t have surgery to remove your ovaries, you may have CA125 every 4 months.
Have symptoms? See your GP, who can order CA125 on the NHS. For other markers, see blood tests for cancer.
When to speak to a GP
The NHS and NICE say to see a GP if:
- You have bloating, feel full quickly, have tummy or pelvic pain, or need to pee more, roughly 12 or more times a month.
- You have other possible signs: indigestion, constipation or diarrhoea, back pain, feeling tired all the time or losing weight without trying.
- You have unusual bleeding from the vagina, including between periods, heavier periods or after the menopause.
- You’ve seen a GP before, but your symptoms haven’t gone away, are worse or happen more often.
- You’re 50 or over and have new IBS-type symptoms from the last 12 months.
Get an urgent GP appointment or call 111 if you have sudden, severe pelvic pain, or tummy pain and feel or are being sick.
These symptoms are very common and can have many causes. Called back about a result? Read when your GP wants to see you and blood test reference ranges.