Polycystic Ovary Syndrome (PCOS) is one of the most common endocrine conditions, but its presentation and impact vary enormously from person to person. Some individuals experience regular menstrual cycles yet have significant biochemical signs of hyperandrogenism, while others have irregular periods without elevated androgen levels. Understandably, this variability can be confusing—especially when friends or the media (often mistakenly linking PCOS with endometriosis) describe vastly different experiences.
I often explain to patients that PCOS is not a single disease but a syndrome—a spectrum of ovulatory, pituitary, and sometimes adrenal dysfunctions. A formal classification system helps us understand the range of presentations:
| Phenotype | Features |
|---|---|
| A | Hyperandrogenism, anovulation/oligomenorrhoea, and polycystic ovarian morphology (PCOM) on ultrasound |
| B | Hyperandrogenism and anovulation/oligomenorrhoea, but normal ovarian appearance |
| C | Hyperandrogenism and PCOM, with regular menstrual cycles |
| D | Anovulation/oligomenorrhoea and PCOM, without evidence of hyperandrogenism |
What These Phenotypes Mean
- Phenotype A is often referred to as “classic PCOS” and is typically associated with elevated AMH and DHEAS levels.
- Phenotype B tends to occur more frequently in individuals with higher BMI and often responds well to weight loss and insulin-sensitising therapies like metformin or GLP-1 receptor agonists.
- Phenotype C is usually found in people with lean PCOS, often showing a high LH:FSH ratio, suggesting underlying pituitary involvement.
- Phenotype D is sometimes debated in terms of diagnostic clarity. It can resemble Functional Hypothalamic Amenorrhoea (FHA), so I look at LH/FSH levels, markers of low energy availability (e.g. fT3, IGF-1), and insulin resistance, and may perform a progesterone challenge test. In some cases, dual treatment for PCOS and FHA is warranted.
Debunking Online Myths
You may come across terms like “insulin-resistant PCOS,” “inflammatory PCOS,” “adrenal PCOS,” or even “post-pill PCOS” online. These are not part of any formally recognised classification and are often misleading. Most individuals with PCOS exhibit some level of insulin resistance and systemic inflammation. Adrenal androgens (like DHEAS) may be elevated alongside total testosterone but don’t define a distinct subtype.
Personalised Care Is Key
Ultimately, PCOS doesn’t come in a neat box. Symptoms and treatment goals shift throughout a person’s life—whether it’s managing acne, cycle regulation, fertility, or long-term metabolic health. That’s why personalised assessment and treatment matter so much.