PCOS Phenotypes Explained: Understanding the Different Types of PCOS

Quick Facts

• PCOS is a heterogeneous condition, meaning symptoms and drivers vary between individuals.
• There are four recognised PCOS phenotypes (A–D), based on hormone levels, ovulation and ovarian appearance.
• Some phenotypes are more metabolically driven, while others are more hormone-driven.
• Understanding your phenotype can help guide more targeted testing and management.

Polycystic Ovary Syndrome (PCOS) is one of the most common hormonal conditions affecting women with ovaries – but it doesn’t always look the same from person to person.

That’s because PCOS isn’t a single, uniform condition. It has different phenotypes, or subtypes, depending on how it presents.

Let’s break it down.

What Is PCOS?

Polycystic Ovary Syndrome (PCOS) is a hormonal disorder that affects how the ovaries function.

It can lead to:

• Irregular or absent periods
• High levels of androgens (male hormones)
• Multiple small follicles on the ovaries (often called polycystic ovaries)

It can also be linked to weight gain, acne, excess hair growth (hirsutism), fertility challenges, and insulin resistance.

But not everyone with PCOS experiences all of these.

The Four PCOS Phenotypes Explained

Medical guidelines group PCOS into four phenotypes based on a combination of three key features:

1. Irregular ovulation (O)
2. High androgens (A)
3. Polycystic ovaries on ultrasound (P)

Phenotype A:

“Classic” PCOS

(Hyperandrogenism + Ovulatory Dysfunction + Polycystic Ovaries)

Phenotype B:

Non-Polycystic Ovary PCOS

(Hyperandrogenism + Ovulatory Dysfunction)

Phenotype C:

Ovulatory PCOS

(Hyperandrogenism + Polycystic Ovaries)

Phenotype D:

Non-Hyperandrogenic PCOS

(Ovulatory Dysfunction + Polycystic Ovaries)

Here are the types:

Each phenotype represents a different combination of hormonal imbalance, ovarian function and metabolic features – which is why symptoms and long-term risks can vary significantly between individuals.

Why PCOS Phenotypes Matter

Understanding your PCOS phenotype can help tailor treatment:

• Some types respond better to lifestyle changes or medications like metformin.
• Others may need specific hormone management or fertility support.
• Metabolic risks (like insulin resistance or diabetes) are higher in some phenotypes than others.

Diagnosis should always be based on a full medical history, blood tests, and ultrasound – not just symptoms.

How PCOS Phenotypes Affect Symptoms

Some phenotypes present with more visible symptoms (acne, hair growth).

Others may present with metabolic issues (insulin resistance, fatigue).

Some may have regular cycles but still have underlying hormonal imbalance.

FAQ

What are the 4 types of PCOS?

• PCOS is classified into four phenotypes (A–D), based on combinations of high androgen levels, ovulatory dysfunction and polycystic ovarian morphology.

Which PCOS phenotype is most common?

• Phenotype A, often referred to as “classic PCOS,” is the most commonly diagnosed and typically presents with the most pronounced symptoms.

Why does PCOS present differently in different people?

• Because PCOS involves multiple systems – hormonal, metabolic and reproductive – the way it presents depends on which systems are most affected.

Final Word

PCOS is a spectrum – not a one-size-fits-all diagnosis.

Knowing your specific phenotype can empower you to work with your healthcare provider toward personalised, effective care.