PCOS: Symptoms, Causes and the Tests That Help Diagnose It

Irregular periods put down to stress. Acne blamed on hormones settling. For a lot of women, the road to a PCOS diagnosis looks like a series of separate explanations for symptoms that were connected all along.

Polycystic ovary syndrome, now being renamed polyendocrine metabolic ovarian syndrome (PMOS) as UK guidelines update, affects around one in ten women in the UK. It's one of the most common hormonal conditions there is and also one of the most frequently missed. The World Health Organisation estimates that around 70% of women who have it don't know.

Here's what to look for, what sits behind it, and which tests help build a clearer picture.

What is PCOS?

PCOS is a hormonal condition that affects how the ovaries work. In women with PCOS, the ovaries produce higher levels of androgens; these are hormones such as testosterone that everyone has, but usually in smaller amounts in women. That imbalance disrupts ovulation, and the knock-on effects show up across the body.

The name causes a fair bit of confusion, and understandably so. The "cysts" aren't really cysts at all. They're follicles: small fluid-filled sacs where eggs develop but never quite mature enough to be released. You can have polycystic ovaries without having PCOS, and you can have PCOS without polycystic ovaries showing on a scan. The condition affects the whole body, which is part of why it takes so long to spot.

That naming problem has now been formally addressed. In May 2026, an international consensus published in The Lancet renamed the condition polyendocrine metabolic ovarian syndrome, or PMOS, dropping the reference to cysts and recognising that this is a hormonal and metabolic condition affecting multiple systems, not just a reproductive one.

The change is being rolled out over three years, so you'll see both names in use for a while yet. Your diagnosis and your treatment don't change.

The symptoms of PCOS

Symptoms vary enormously from one woman to the next, and they often change over time. Most fall into three groups.

Changes to your periods and ovulation

• Irregular periods, cycles consistently longer than 35 days, or fewer than eight a year
• Periods that stop altogether
• Heavier or unpredictable bleeding
• Difficulty conceiving

Signs of raised androgens

• Excess hair growth on the face, chest, back or stomach (hirsutism)
• Persistent acne, particularly along the jawline
• Thinning hair on the scalp

Metabolic and other signs

• Weight gain, often around the middle, or difficulty losing weight
• Darkened patches of skin on the neck, armpits or groin
• Skin tags
• Fatigue

There's a mental health side too, which tends to get overlooked. Women with PCOS are around three times more likely to be diagnosed with depression or anxiety than women without it, partly because of the hormonal picture itself, partly because of the symptoms and the wait for answers.

You don't need all of these symptoms to be diagnosed with PCOS. Some women have two or three; some have almost the full list.

What causes PCOS?

Nobody knows exactly, but three factors show up consistently.

Insulin resistance. When the body doesn't respond well to insulin, it produces more of it to compensate. Those higher insulin levels then prompt the ovaries to make more testosterone, which is what drives many of the symptoms above. It's thought to affect somewhere between half and three-quarters of women with PCOS, and it isn't limited to women who are overweight.

Raised androgens. Higher testosterone levels interfere with the normal development of follicles, so ovulation becomes irregular or stops. They're also behind the hair and skin changes.

Genetics. PCOS often runs in families. If your mother or sister has it, or there's type 2 diabetes in the family, your risk is higher. It's also more common in women of South Asian heritage, who tend to develop symptoms earlier and are at greater metabolic risk. One UK community study found polycystic ovaries in 52% of women of South Asian origin, compared with 22% in a predominantly white population.

How is PCOS diagnosed?

There's no single test for PCOS. Diagnosis is made using the Rotterdam criteria, which means meeting two out of these three:

• Irregular or absent periods: a sign that ovulation isn't happening reliably
• Signs of raised androgens: either visible symptoms such as excess hair growth, or a blood test showing high levels
• Polycystic ovaries on an ultrasound scan: a high number of follicles, or enlarged ovaries

Because it's two out of three, the combinations vary. You can be diagnosed with irregular periods and a scan showing polycystic ovaries, even with completely normal testosterone.

There's a second half to the process that gets far less attention: ruling other things out. Several conditions produce similar symptoms, including thyroid problems, raised prolactin levels, and adrenal conditions such as congenital adrenal hyperplasia. A proper assessment checks for these before landing on PCOS.

The tests that help diagnose PCOS

Blood tests can't confirm PCOS on their own, but they do establish whether androgen levels are raised and rule out the conditions that mimic it.

Normal testosterone does not rule out PCOS. Total testosterone comes back within range in roughly a fifth to a third of women who have the condition.

SHBG may still be low, which means the free androgen index is high even when the headline number looks unremarkable. If your testosterone was normal and you were told that settled it, that isn't the full picture.

Timing matters too. Where possible, hormone bloods are best taken on days one to five of your cycle, as testosterone can read misleadingly high later on. If your periods are absent or more than six weeks apart, timing is less relevant.

Getting the most from your GP appointment

A bit of preparation makes a real difference, particularly if you've been dismissed before.

• Track your periods for three months. Dates, length, flow. A written record is much harder to wave away than "they're a bit all over the place."
• List every symptom, including the ones that feel unconnected: fatigue, mood, skin changes, hair.
• Note your family history, including PCOS, type 2 diabetes, irregular periods.
• Ask which tests are being run and why. If testosterone is being checked, ask whether SHBG is included.
• Take any existing results with you. Numbers on paper tend to move things along faster.

Why an early diagnosis matters

PCOS is a lifelong condition, but it's a manageable one. The earlier you know, the more you can do.

Left unrecognised, PCOS carries a raised long-term risk of type 2 diabetes, high blood pressure, high cholesterol and cardiovascular disease. Long gaps between periods can also affect the lining of the womb over time, which is why most guidance suggests aiming for a period at least three or four times a year. And if you're thinking about pregnancy, knowing sooner gives you far more room to plan.

None of that is inevitable. Insulin resistance responds well to changes in diet and activity; symptoms can be treated, and risks can be monitored once someone knows to look for them. All of it starts with knowing what you're dealing with.

Taking the next step

If you've got symptoms and you're not getting answers, a health assessment can tell you more about what's going on.

Our hormone profiles measure the markers that matter here, including SHBG, FSH and thyroid function, alongside checks such as HbA1c and cholesterol that speak to your longer-term metabolic and cardiovascular risk.

You'll get a personalised Results Report explaining every reading in plain English, with each one flagged green, amber or red so you can see at a glance where to focus. Results are available through My Wellness, some in as little as three days, and you can download a PDF to take straight to your GP.

A private blood test supports a diagnosis rather than replacing one. Only a doctor can diagnose PCOS. What a Bluecrest assessment gives you is evidence and a much better conversation when you sit down with them.

Find a clinic near you and book an appointment at a time that suits you.

Live healthier for longer with Bluecrest health intelligence.

Frequently asked questions

Is PCOS now called something else?

Yes. In May 2026, the condition was formally renamed polyendocrine metabolic ovarian syndrome (PMOS) by international consensus, to reflect that it affects hormones and metabolism rather than just the ovaries. The change is being phased in over three years. The condition, the criteria and the treatment are all unchanged.

Can you have PCOS without cysts?

Yes. The scan is only one of the three Rotterdam criteria, and you need two of the three. Plenty of women are diagnosed on the basis of irregular periods and raised androgens with a completely normal ultrasound.

Can a blood test alone diagnose PCOS?

No. A blood test can confirm raised androgens and rule out conditions with similar symptoms, but diagnosis also takes into account your symptoms, your cycle and sometimes a scan. It's useful evidence rather than giving the full picture.

Is PCOS the same as having polycystic ovaries?

No, and this trips a lot of people up. Polycystic ovaries show up on ultrasound in roughly one in five women. Only around 5–10% of them go on to have the full syndrome, because the others don't meet the remaining criteria.

Does PCOS go away after the menopause?

Periods stop, so that particular symptom resolves. But the metabolic side (insulin resistance, cardiovascular risk) doesn't disappear, and it's worth continuing to monitor.

Can you get pregnant with PCOS?

Yes. PCOS can make conceiving harder because ovulation is irregular, but many women with PCOS conceive naturally. Treatments are available where they're needed, and getting a diagnosis early gives you more options.