PCOS: Understanding What Is Really Driving Polycystic Ovary Syndrome

Polycystic Ovary Syndrome (PCOS) is one of the most common endocrine conditions affecting women of reproductive age. Despite its prevalence, it remains one of the most misunderstood conditions in women’s health.

Many women are told they have “cysts on their ovaries” and are prescribed hormonal contraception without ever being given a clear explanation of what is actually happening within the body.

The reality is far more complex.

PCOS is not simply an ovarian condition. It is a heterogeneous metabolic and hormonal disorder involving communication between the brain, ovaries, adrenal glands, insulin signalling pathways and the reproductive hormone axis.

Understanding these mechanisms is essential if we want to move beyond symptom management and begin addressing the factors contributing to the condition.

What Is PCOS?

PCOS is characterised by two key features:

• Excess androgen production (male-type hormones such as testosterone)

• Ovulatory dysfunction

  
  

Women with PCOS commonly experience:

• Irregular or absent periods

• Acne

• Excess facial or body hair (hirsutism)

• Scalp hair thinning

• Difficulty conceiving

• Weight gain or difficulty losing weight

• Ovarian changes visible on ultrasound

  
  

Importantly, acne, unwanted hair growth and obesity do not cause PCOS. They are symptoms resulting from the underlying hormonal disturbances.

The condition is most commonly diagnosed during a woman’s twenties and thirties, although the underlying processes often begin much earlier.

Why Ovulation Matters

Many discussions around PCOS focus on fertility, but ovulation influences far more than the ability to conceive.

Regular ovulatory cycles contribute to:

• Healthy progesterone production

• Bone integrity

• Mood regulation

• Metabolic health

• Mitochondrial energy production

• Cardiovascular health

• Neurotransmitter function

When ovulation becomes irregular or absent, progesterone production is reduced.

This creates a hormonal environment where oestrogen remains relatively unopposed and androgen production often increases.

Over time, this can affect everything from mood and energy levels to metabolic function and endometrial health.

Understanding A Normal Menstrual Cycle

To understand PCOS, it helps to understand what should happen during a healthy cycle.

At the beginning of the menstrual cycle, levels of oestradiol and progesterone are low.

In response, the hypothalamus and pituitary gland signal the ovaries through the release of:

• Follicle-stimulating hormone (FSH)

• Luteinising hormone (LH)

  
  

Each month, a group of ovarian follicles begins developing.

Although hundreds of follicles are recruited, only one typically becomes dominant and proceeds to ovulation.

Within the ovary:

• Theca cells produce androgens

• Granulosa cells convert those androgens into oestrogen via the aromatase enzyme

  
  

As the dominant follicle grows, oestradiol levels rise.

This eventually triggers the mid-cycle LH surge responsible for ovulation.

Following ovulation, the follicle transforms into the corpus luteum, which produces progesterone.

Progesterone prepares the uterine lining for pregnancy and helps regulate the second half of the menstrual cycle.

If pregnancy does not occur, progesterone falls and menstruation begins.

What Happens In PCOS?

In PCOS, this finely tuned communication system becomes disrupted.

Instead of the normal rhythmic release of GnRH from the hypothalamus, abnormal pulse patterns develop.

These altered signals favour LH production.

As a result:

• LH levels become chronically elevated

• FSH remains relatively lower

• Theca cells produce excessive androgens

• Follicle development slows or stalls

• Ovulation becomes delayed or absent

Rather than progressing to ovulation, many follicles remain trapped in a partially developed state.

These are often described as “cysts”, but they are not true cysts.

They are immature follicles that have failed to complete development.

This distinction is important because PCOS cannot be ruled in or ruled out solely on the basis of an ultrasound scan.

Why Excess Androgens Matter

Excess androgen production is one of the defining features of PCOS.

Higher androgen levels can contribute to:

• Facial hair growth

• Acne

• Oily skin

• Hair thinning around the crown of the head

• Irregular cycles

• Impaired ovulation

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The most potent androgen, dihydrotestosterone (DHT), is produced through the action of the enzyme 5-alpha reductase.

This enzyme is often a therapeutic target when addressing androgen-related symptoms.

The Role of Insulin Resistance

One of the most important drivers of PCOS is insulin resistance.

Research suggests that approximately 75-80% of women with PCOS demonstrate some degree of impaired insulin sensitivity.

When insulin levels remain elevated:

• Insulin directly stimulates ovarian theca cells

• Insulin mimics some of the actions of LH

• Sex hormone binding globulin (SHBG) decreases

• Free testosterone increases

  
  

This creates a cycle where elevated insulin drives greater androgen production, which then further disrupts ovulation.

For many women, hyperinsulinaemia sits at the centre of the condition.

It is one reason why blood sugar regulation and metabolic health are often critical components of treatment.

Why Heavy Periods Can Occur

Without regular ovulation, progesterone production is reduced.

Oestradiol continues stimulating growth of the endometrial lining, but the balancing effects of progesterone are absent.

Over time this can contribute to:

• Endometrial hyperplasia

• Heavy bleeding

• Large clots

• Irregular bleeding patterns

  
  

This is one reason prolonged absence of ovulation should never be ignored.

Diagnosing PCOS: Why It Can Be Confusing

Historically, diagnosis focused heavily on androgen excess and ovulatory dysfunction.

The Rotterdam Criteria introduced in 2003 broadened the definition.

Under these guidelines, PCOS could be diagnosed if two of the following three features were present:

• Clinical or biochemical androgen excess

• Ovulatory dysfunction

• Polycystic ovaries on ultrasound

  
  

This change meant some women could receive a diagnosis based on irregular periods and ultrasound findings alone, even without clear evidence of androgen excess.

The 2023 international guidelines continue to use a two-out-of-three framework whilst recognising the role of Anti-Müllerian Hormone (AMH) as an additional diagnostic tool in adults.

Importantly, ultrasound and AMH are not recommended as diagnostic tools within eight years of menarche because the reproductive system is still maturing and irregular cycles are often physiological.

Laboratory Assessment

A thorough assessment should consider:

• Total testosterone

• Free androgen index

• Sex hormone binding globulin (SHBG)

• LH

• FSH

• Anti-Müllerian Hormone (AMH)

• Fasting insulin

• Blood glucose regulation

• Prolactin

• Thyroid function

• 17-hydroxyprogesterone

• DHEA-S

  
  

When evaluating testosterone, laboratory methodology matters.

Liquid chromatography tandem mass spectrometry (LC-MS/MS) is generally considered the gold standard for measuring female androgens.

Conditions That Can Mimic PCOS

Not every woman with elevated androgens has PCOS.

Other causes must be considered, including:

• Congenital adrenal hyperplasia

• Elevated prolactin

• Thyroid dysfunction

• Adrenal androgen excess

• Certain medications

• Hormonal contraception

  
  

For example, deficiencies in the enzyme 21-hydroxylase can lead to increased androgen production and may resemble PCOS.

Likewise, elevated prolactin can suppress normal LH and FSH signalling and disrupt ovulation.

A Functional Medicine Perspective

PCOS is unlikely to be a single disease with a single cause.

Different women may present with different dominant drivers.

These commonly include:

Insulin-resistant PCOS

Characterised by:

• Elevated insulin

• Weight gain

• Cravings

• Difficulty losing weight

• Elevated free testosterone

  
  

Adrenal PCOS

Characterised by:

• Elevated DHEA-S

• Stress-related symptoms

• Anxiety

• Sleep disruption

• Relatively normal insulin levels

  
  

Post-pill PCOS

Symptoms may emerge following cessation of hormonal contraception, particularly after prolonged suppression of the hypothalamic-pituitary-ovarian axis.

Inflammatory PCOS

Low-grade inflammation may contribute to androgen production through inflammatory signalling pathways involving CRP, IL-6 and NF-kB.

Supporting Healthy Hormone Balance

Management should always be individualised and based on the underlying drivers.

Potential areas of support may include:

• Improving insulin sensitivity

• Supporting ovulation

• Reducing excess androgen production

• Addressing stress and adrenal dysfunction

• Correcting nutrient deficiencies

• Improving sleep quality

• Supporting healthy body composition

• Investigating gut and inflammatory contributors

  
  

Inositol

Myo-inositol plays an important role in insulin signalling, ovarian function and follicular development.

Research suggests it may:

• Improve insulin sensitivity

• Reduce androgen levels

• Improve ovulation

• Increase SHBG

• Improve LH:FSH ratios

  
  

Products using a physiological 40:1 ratio of myo-inositol to D-chiro-inositol are commonly used in PCOS.

Nutrients and Botanicals

Several nutrients and plant compounds have been investigated for their effects on androgen metabolism, including:

• Zinc

• Spearmint tea

• Green tea

• Reishi mushroom

• Liquorice root

• Paeonia (Chinese peony)

• Nettle root

Many work through mechanisms involving androgen production, aromatase activity or 5-alpha reductase inhibition.

Progesterone

For some women, cyclical micronised progesterone may be considered under medical supervision.

Potential benefits include:

• Supporting regular withdrawal bleeds

• Protecting the endometrium

• Reducing DHT formation

• Supporting more normal GnRH and LH signalling patterns

The Bigger Picture

PCOS is far more than a collection of ovarian cysts.

It is a complex hormonal and metabolic condition involving communication between the brain, ovaries, adrenal glands and insulin signalling pathways.

The presence of excess androgens, disrupted ovulation and metabolic dysfunction can influence fertility, mood, energy production, body composition and long-term health.

Understanding the underlying drivers allows for a more personalised approach that goes beyond symptom suppression and focuses on restoring healthy hormonal signalling, metabolic resilience and ovulatory function.