What Is PMOS? Symptoms, Diagnosis, Hormones and Metabolic Health Explained

Quick Facts

 

• PMOS was previously called PCOS, changed in May 2026.
• PMOS encompasses diverse endocrine, metabolic, reproductive, psychological, and dermatological features. The previous name (PCOS) reflected only one organ and failed to capture the disorder’s multi-system nature.
• PMOS affects around 1 in 8 women worldwide.
• You do not need ovarian cysts to have PMOS – the structures previously described as “cysts” are actually increased numbers of small ovarian follicles.
• There is no single blood test for PMOS.
• Insulin resistance is important – but PMOS is not simply an insulin-resistance condition.
• PMOS can occur at any body size.

 

What does PMOS stand for?

 

PMOS stands for:

Polyendocrine Metabolic Ovarian Syndrome

The condition was previously called Polycystic Ovary Syndrome (PCOS).

The global change was announced on 12 May 2026 after a 14-year international process involving healthcare professionals, researchers, professional organisations and people with lived experience.

The previous name created two major problems.

Firstly, “polycystic” suggested that the condition was caused by ovarian cysts. It isn’t.

Secondly, placing the ovary at the centre of the name significantly underestimated the wider endocrine and metabolic features of the condition.

The new terminology reflects a condition that reaches far beyond one organ.

Importantly, PMOS and PCOS are not different conditions. If you were previously diagnosed with PCOS, your diagnosis has not suddenly changed – the terminology has.

 

 

What actually happens in PMOS?

 

There is no single biological abnormality responsible for every case of PMOS.

Instead, several interconnected systems can become involved.

Three particularly important areas are:

Androgen signalling

 

Androgens include hormones such as testosterone.

Higher androgen concentrations – or increased androgen activity – can contribute to symptoms including:

• Acne
• Increased facial or body hair
• Scalp hair thinning
• Disruption of normal ovulation.

Not everyone with PMOS will have dramatically elevated testosterone on a blood test.

Clinical signs of androgen excess can also form part of the diagnostic picture.

 

Ovulation and reproductive hormone signalling

 

Normal ovulation depends on coordinated signalling between the brain, pituitary gland and ovaries.

In PMOS, follicular development and ovulation can become disrupted.

This may result in:

• Irregular cycles
• Long gaps between periods
• Absent periods
• Reduced frequency of ovulation.

But having relatively regular periods does not automatically exclude PMOS.

 

Metabolic and insulin signalling

 

Insulin allows glucose to move from the bloodstream into cells where it can be used for energy.

In insulin resistance, cells become less responsive to insulin and the body may compensate by producing more.

Higher insulin exposure can interact with ovarian androgen production and can also reduce production of sex hormone-binding globulin (SHBG) in the liver.

Lower SHBG can increase the proportion of testosterone that is biologically available.

This creates one of several possible links between:

metabolism → insulin → androgen activity → ovulation

But it is important not to oversimplify this either.

Not everyone with PMOS has the same degree of insulin resistance, and insulin resistance is not the only mechanism involved.

 

What causes PMOS?

 

We still cannot point to one single cause.

PMOS appears to develop through a combination of genetic, endocrine, metabolic and environmental influences.

Family history matters, and the condition frequently clusters within families.

Research also points towards interactions involving:

genetic susceptibility, androgen signalling, insulin sensitivity, ovarian function, neuroendocrine signalling, body composition and potentially wider factors including the gut microbiome.

This is one reason the idea of finding a single “root cause” for every woman with PMOS is unlikely to reflect the true biology.

PMOS is heterogeneous.

In simple terms:

different people can reach a similar diagnosis through somewhat different biological patterns.

 

 

What are the symptoms of PMOS?

 

PMOS symptoms vary considerably between individuals and may also change throughout life.

 

Menstrual and ovulatory symptoms

 

These can include:

• Irregular periods
• Long menstrual cycles
• Infrequent periods
• Absent periods
• Difficulty identifying ovulation
• Anovulatory cycles

 

Androgen-related symptoms

 

Higher androgen activity may contribute to:

• Persistent acne
• Oily skin
• Increased facial hair
• Increased body hair
• Scalp hair thinning
• Androgenic-pattern hair loss

 

Metabolic signs and symptoms

 

Some people may experience:

• Weight gain
• Difficulty managing weight
• Central weight distribution
• Impaired glucose regulation
• Insulin resistance
• Acanthosis nigricans – darker, thickened areas of skin, often around the neck or underarms
• Changes in cholesterol or triglycerides

 

PMOS can, however, occur across the full range of body sizes.

Someone does not need to have overweight or obesity to have PMOS or to require assessment of their metabolic health.

 

Reproductive symptoms

 

Disrupted ovulation can make conception more difficult for some people.

PMOS is therefore a common cause of anovulatory infertility.

However, PMOS does not mean that someone cannot become pregnant.

Many women with PMOS conceive naturally, while others may require support to restore or induce ovulation.

 

 

Psychological and quality-of-life effects

 

The psychological aspect of PMOS should not be treated as an afterthought.

International guidance recognises a higher prevalence of depression and anxiety, alongside potential effects on body image, eating behaviours, psychosexual wellbeing and overall quality of life.

That means a proper PMOS assessment should involve more than hormones and ovaries.

 

 

How is PMOS diagnosed?

 

There is no single test that diagnoses PMOS.

For adults, current international evidence-based guidance uses updated Rotterdam-style diagnostic criteria.

After other potential causes have been excluded, diagnosis generally requires two of the following three features:

 

 1. Ovulatory dysfunction

For example, irregular or absent menstrual cycles suggesting that ovulation is not happening regularly.

 

 2. Clinical or biochemical hyperandrogenism

This could mean signs such as hirsutism, or biochemical evidence from appropriately performed androgen testing.

 

 3. Polycystic ovarian morphology

This can be assessed by ultrasound.

 

In adults, appropriately measured Anti-Müllerian Hormone (AMH) may now be used as an alongside ultrasound imagery for determining polycystic ovarian morphology within the diagnostic algorithm.

It should not simply be used as a standalone “PMOS test”.

If someone already has both irregular cycles and clear evidence of hyper-androgenism, an ultrasound or AMH test may not be needed to establish the diagnosis.

 

 

Can you have PMOS without ovarian cysts?

 

Yes!

This is one of the most persistent misconceptions surrounding the condition.

 

The structures traditionally described as polycystic ovaries are actually increased numbers of small ovarian follicles, not pathological ovarian cysts in the conventional sense.

And because only two of the three main diagnostic features are required in adults, someone can meet diagnostic criteria without polycystic ovarian morphology at all.

This was one of the major reasons the old PCOS terminology became increasingly problematic.

 

 

What blood tests are used when investigating PMOS?

 

Testing should be guided by symptoms, menstrual history, medication use and the wider clinical picture.

There is no universal panel required for every person, but investigations may include several areas.

 

Androgen Assessment

 

Testing may include:

• Total Testosterone
• SHBG – Sex Hormone-Binding Globulin
• Calculated Free Testosterone or Free Androgen Index, depending on laboratory methodology
• DHEA-S

In some situations, pregnenolone and androstenedione may also be considered.

 

The method used to measure androgens matters, particularly at the relatively low concentrations found in women.

Hormonal contraception can also make biochemical assessment considerably more difficult because it can alter SHBG and androgen concentrations.

 

Other reproductive and endocrine markers

 

Depending on the presentation, clinicians may consider markers such as:

• Follicle Stimulating Hormone (FSH)
• Luteinising Hormone (LH)
• Oestradiol (E2)
• Prolactin
• TSH and thyroid hormones where appropriate
• 17-hydroxyprogesterone

These are not all markers that “prove PMOS”.

Some are particularly important because other endocrine conditions can mimic parts of the PMOS picture and need to be excluded.

 

Metabolic Assessment

 

PMOS assessment should not finish once testosterone has been measured.

Depending on the individual, consideration may also be given to:

• Fasted glucose regulation
• HbA1c
• Extended Lipid (cholesterol) profile
• Blood pressure

The current international guideline considers the 75 g oral glucose tolerance test – OGTT – the most accurate test for assessing glycaemic status in PMOS, regardless of BMI.

If an OGTT cannot be performed, fasting glucose and/or HbA1c may be considered, although they are less accurate for detecting abnormal glucose regulation in this population.

Interestingly, although insulin resistance is central to the biology of PMOS for many women, current guidelines do not recommend routine insulin assays as a standard diagnostic measure because available clinical insulin tests are not sufficiently reliable for this purpose.

That distinction is important:

insulin resistance matters, but a fasting insulin result alone does not diagnose or exclude PMOS.

 

 

What tests cannot diagnose PMOS on their own?

 

PMOS is a clinical diagnosis built from several pieces of information.

It should not be diagnosed solely from:

 

• A high AMH result
• An ovarian ultrasound
• A single testosterone result
• A single fasting insulin result
• An LH:FSH ratio
• or one symptom in isolation.

 

For example, an elevated LH ratio is sometimes discussed online as though it is a diagnostic PMOS test.

It isn’t always the case in all women with PMOS – some women have not LH:FSH issues throughout the whole of their menstrual cycle when monitored long-term across the menstrual cycle peaks and troughs.

Similarly, AMH can now play a useful role in adult diagnosis, but current guidance explicitly recommends against using AMH as a single diagnostic test.

Context always matters.

 

 

PMOS and Insulin Resistance: what is the connection?

 

This is one of the most important – and most frequently oversimplified – areas of PMOS.

Insulin resistance can lead to compensatory increases in insulin production.

Higher insulin can interact with ovarian cells and promote androgen production while also suppressing liver production of SHBG.

That can contribute to greater free androgen exposure.

 

The relationship can therefore become interconnected:

insulin resistance → higher insulin → increased androgen activity → disrupted ovulation

 

Yet not every person with PMOS follows this exact pattern.

And someone does not have to have obesity to experience impaired glucose regulation.

Current international guidance recommends assessing glycaemic status irrespective of BMI.

This is a major reason why PMOS should be considered a metabolic as well as reproductive condition.

 

 

PMOS and cholesterol, blood pressure and cardiovascular health

 

PMOS is associated with a higher prevalence of cardiovascular risk factors.

These can include:

• Altered lipid profiles
• Impaired glucose regulation
• Type 2 Diabetes
• High blood pressure.

 

This does not mean that every young woman with PMOS is destined to develop cardiovascular disease.

It means cardiovascular and metabolic risk should not be ignored simply because someone initially presented because of acne, irregular periods or fertility.

Current guidance recommends assessing cardiovascular risk factors – including lipid status and blood pressure – as part of longer-term PMOS care.

 

 

PMOS and Mental Health

 

The endocrine and reproductive features of PMOS often receive the most attention.

Mental health deserves equal recognition.

Women with PMOS experience significantly higher rates of depressive and anxiety symptoms than women without the condition.

Several factors may contribute.

These may include biological mechanisms, chronic symptom burden, fertility concerns, weight stigma, unwanted hair growth, acne, scalp hair loss and the psychological effects of living with a poorly understood chronic condition.

International guidelines therefore recommend screening for depression in adults and adolescents with PMOS and for anxiety in adults.

Mental health symptoms should never simply be dismissed as “just hormones”.

 

 

PMOS and sleep: a frequently missed connection

 

Sleep is another area increasingly included in PMOS guidance.

Women with PMOS have a higher prevalence of obstructive sleep apnoea, and importantly, the association is not explained by BMI alone.

Symptoms worth discussing with a clinician include:

• Snoring
• Waking feeling unrefreshed
• Significant daytime sleepiness
• Persistent fatigue.

A sleep questionnaire can help identify people who need further assessment, but diagnosing obstructive sleep apnoea requires a formal sleep study.

This is also an important reminder that fatigue in someone with PMOS should not automatically be attributed to the condition itself.

Iron deficiency, thyroid dysfunction, sleep disorders, nutritional deficiencies and numerous other conditions may also contribute.

 

PMOS, Periods and the Endometrium

 

Long gaps between periods are more than an inconvenience.

When ovulation does not occur regularly, progesterone exposure may also be reduced.

This can leave the endometrium – the lining of the uterus – exposed to oestrogen without the usual cyclical progesterone effect for prolonged periods.

Premenopausal women with PMOS have an increased risk of endometrial hyperplasia and endometrial cancer.

However, the absolute risk of endometrial cancer remains low, which is why routine cancer screening is not recommended solely because someone has PMOS.

Long-standing untreated amenorrhoea, higher body weight, type 2 diabetes and persistent endometrial thickening can further increase risk.

This is why repeatedly going many months without a period should be discussed with a healthcare professional rather than simply accepted as part of PMOS.

 

PMOS and Fertility

 

PMOS is one of the most common causes of ovulatory fertility problems. But PMOS does not equal infertility.

Some women with PMOS ovulate regularly, whilst others ovulate intermittently (some cycles ovulation occurs, other cycles it is ‘missed’).

Some may need treatment to induce ovulation when attempting pregnancy.

Where anovulatory infertility is caused by PMOS and no other infertility factors are present, current international guidance identifies letrozole as the preferred first-line medication for ovulation induction.

The most appropriate fertility pathway still depends on the individual, partner factors, age, ovarian reserve, tubal health and other clinical considerations.

Pregnancy in PMOS also deserves closer monitoring because the condition is associated with increased risks of certain pregnancy complications, including abnormal glucose regulation and hypertensive (blood pressure) disorders.

 

Is PMOS only relevant during reproductive years?

 

No.

The way PMOS presents may change with age, but its health implications are not limited to fertility.

Someone may care deeply about conception at one stage of life and not at another.

The metabolic, cardiovascular, dermatological, psychological and endometrial aspects of PMOS remain relevant regardless of fertility intentions.

Good PMOS care should therefore change alongside the individual.

The question should not simply be:

“Are you trying for a baby?”

It should also be:

“What is affecting your physical and mental health now, and what needs protecting longer term?”

 

 

How is PMOS treated?

 

There is currently no single treatment that works for every person with PMOS, and management should be based on a case to case basis, on the person’s symptoms, metabolic health, reproductive plans and priorities.

Depending on the individual, treatment may involve:

 

Lifestyle Support

 

Healthy eating patterns, physical activity, sleep and wider lifestyle factors are recommended for overall health in PMOS.

Importantly, lifestyle interventions can provide health benefits even without weight loss.

Weight stigma should not form part of PMOS care.

 

Cycle Regulation

 

Hormonal contraception or periodic progestogen treatment may be considered in some people to regulate bleeding, manage symptoms and protect the endometrium.

 

Insulin Sensitisation

 

Metformin may be considered in appropriate patients, particularly where metabolic features are present.

 

Androgen-related symptoms

 

Treatment may include hormonal contraception, anti-androgen therapy in appropriately selected patients, dermatological treatments and targeted approaches for acne, hirsutism or hair loss.

Anti-androgen medication requires appropriate medical supervision and effective contraception where pregnancy is possible.

 

Fertility treatment

 

Where ovulation is the primary issue, treatments can be used to induce ovulation.

 

Psychological support

 

Anxiety, depression, eating concerns, body-image difficulties and reduced quality of life should be actively recognised and managed where present.

 

The goal is not simply to “normalise hormones”.

It is to address the aspects of PMOS that matter to the person living with it.

 

 

PMOS is not one condition with one look

 

Perhaps one of the most useful things we can understand about PMOS is that it is heterogeneous.

 

• There is no universal appearance.

 

• No universal hormone pattern.

 

• No universal metabolic profile.

 

• And no universal symptom list.

 

One person may experience significant androgen-related symptoms and relatively little metabolic disruption.

Another may have substantial insulin resistance without obvious hirsutism or acne.

Another may appear to menstruate fairly regularly but meet diagnostic criteria through hyperandrogenism and ovarian morphology.

This variation is why reducing PMOS to “cysts”, weight, testosterone or fertility alone misses the bigger picture.

 

You can read further upon PMOS Phenotypes, how they present here: PMOS Phenotypes Explained — Understanding the Different Types of PMOS

 

 

When should you investigate possible PMOS?

 

Consider speaking with a GP or appropriate healthcare professional if you experience persistent features such as:

• Consistently irregular or absent periods
• Significant changes in facial or body hair
• Persistent adult acne
• Unexplained scalp hair thinning
• Difficulty ovulating or conceiving
• Signs suggestive of impaired glucose regulation
• Long gaps between menstrual bleeds
• Symptoms affecting your physical or psychological wellbeing

These symptoms are not specific to PMOS.

Thyroid disorders, elevated prolactin, hypothalamic amenorrhoea, non-classic congenital adrenal hyperplasia, pregnancy, some medications and other endocrine conditions can produce overlapping features.

Proper assessment matters precisely because not every irregular period or high testosterone result is PMOS.

 

The My Atlas view

 

The move from PCOS to PMOS represents a wider shift in how we have always approached about the condition.

Away from: ovaries alone

and towards: endocrine + metabolic + reproductive + psychological health.

That does not mean every possible biomarker needs testing, it means testing should answer a clinical question.

If androgen symptoms are present, investigate androgen biology appropriately.

If periods are irregular, understand whether ovulation is occurring and exclude other endocrine causes.

If PMOS is diagnosed, do not forget glucose regulation, cardiovascular risk, sleep, mental health and longer-term reproductive health.

Complex health rarely comes down to one abnormal result.

And PMOS is a particularly good example of why the wider context matters.

 

 

Frequently Asked Questions

 

What is PMOS?

 

PMOS stands for Polyendocrine Metabolic Ovarian Syndrome. It is the new name for the condition previously known as Polycystic Ovary Syndrome or PCOS.

It is a complex endocrine and metabolic condition that can affect hormones, ovulation, periods, metabolism, skin, hair, fertility and psychological wellbeing.

 

Is PMOS the same as PCOS?

 

Yes. PMOS and PCOS refer to the same condition.

The official terminology changed internationally in May 2026 to better reflect the hormonal and metabolic nature of the condition.

 

Why was PCOS renamed PMOS?

 

PCOS suggested that the condition was primarily caused by ovarian cysts. In reality, the ovarian features are follicles rather than conventional cysts, and many people with the condition do not have polycystic ovarian morphology.

PMOS better reflects the wider endocrine and metabolic biology.

 

Can you have PMOS without cysts?

 

Yes. Ovarian cysts are not required for a PMOS diagnosis.

In adults, diagnosis generally requires two of three features: ovulatory dysfunction, hyperandrogenism and polycystic ovarian morphology – with AMH able to substitute for ultrasound in appropriate adults.

 

Can you have PMOS with regular periods?

 

Yes. Some people with PMOS have apparently regular cycles and may meet diagnostic criteria through other features.

Regular bleeding also does not always guarantee that ovulation is occurring normally.

 

What hormone levels are high in PMOS?

 

Androgen activity, including testosterone, can be increased.

However, not every person with PMOS has markedly elevated testosterone. Hormonal patterns differ between individuals, which is why diagnosis cannot be based on a single hormone result.

 

Is LH high in PMOS?

 

LH can be elevated in some people with PMOS, and an increased LH ratio is sometimes observed.

However, the LH ratio is not a diagnostic test for PMOS.

 

Is AMH high in PMOS?

 

AMH is frequently higher in women with PMOS because increased numbers of developing ovarian follicles can produce more AMH. I

n adults, AMH can now be used within the formal diagnostic algorithm as an alternative to ultrasound for assessing polycystic ovarian morphology.

It should not be used as a standalone PMOS test.

 

Does everyone with PMOS have insulin resistance?

 

No. Insulin resistance is an important biological feature of PMOS and is common, but its severity differs considerably between individuals.

 

What is the best test for insulin resistance in PMOS?

 

There is no simple routine blood test that perfectly measures insulin resistance.

For assessing glycaemic status, international PMOS guidelines recommend a 75 g oral glucose tolerance test as the most accurate available test, regardless of BMI. Routine insulin assays are not currently recommended as a standard diagnostic tool.

Can someone be slim and still have PMOS?

 

Yes. PMOS occurs across a range of body sizes. A lower BMI does not exclude PMOS and does not remove the need to consider metabolic health where appropriate.

 

Does PMOS cause weight gain?

 

PMOS can be associated with metabolic changes that make weight management more difficult for some people, but experiences vary significantly. Weight gain is not required for diagnosis.

 

Can PMOS cause hair loss?

 

Yes. Increased androgen activity can contribute to female-pattern scalp hair thinning in some women with PMOS.

Hair loss can have many other causes as well, including iron deficiency, thyroid dysfunction and telogen effluvium, so other contributors may need investigation.

 

Can PMOS cause fatigue?

 

Fatigue is reported by some people with PMOS but is non-specific.

Sleep apnoea is more common in PMOS, while iron deficiency, thyroid disorders, nutritional deficiencies, poor sleep and other health conditions can also cause fatigue and should not automatically be attributed to PMOS.

 

Can PMOS affect mental health?

 

Yes. Depression and anxiety are more common in people with PMOS, and current guidelines recommend appropriate mental-health screening.

 

Does PMOS affect fertility?

 

PMOS can make conception more difficult when ovulation is irregular or absent. However, many women with PMOS conceive naturally, and effective fertility treatments are available when needed.

 

Can PMOS be cured?

 

There is currently no cure for PMOS. However, symptoms, metabolic risk and reproductive health can often be managed effectively, and treatment can be adapted as someone’s priorities change throughout life.

 

What blood tests should I have for PMOS?

 

There is no single universal PMOS panel. Testing may include androgen assessment such as testosterone and SHBG, alongside investigations used to exclude conditions that can mimic PMOS.

Metabolic assessment, including glucose and lipid status, may also be appropriate. Testing should be guided by symptoms and clinical history rather than ordering every hormone available.

 

Should PMOS be monitored even if I am not trying to conceive?

 

Yes. PMOS extends beyond fertility. Longer-term monitoring may include glucose regulation, blood pressure, lipid status, menstrual regularity, mental health and symptoms suggestive of sleep apnoea.

 

References

Teede HJ, Tay CT, Laven JJE, et al. Recommendations from the 2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome. Journal of Clinical Endocrinology & Metabolism. 2023.

International Evidence-based Guideline for the Assessment and Management of Polyendocrine Metabolic Ovarian Syndrome. Monash Centre for Health Research and Implementation.

International consensus on the renaming of Polycystic Ovary Syndrome to Polyendocrine Metabolic Ovarian Syndrome. The Lancet. May 2026.

Endocrine Society. Polyendocrine Metabolic Ovarian Syndrome: New name to improve diagnosis and care of condition affecting 170 million women worldwide. May 2026.