What Is PCOS?
Polycystic ovary syndrome (PCOS) is a common hormonal condition characterised by a combination of features relating to ovulation, androgen levels, and ovarian appearance on ultrasound. Despite its name, having "polycystic" ovaries on ultrasound is neither sufficient nor required for diagnosis — what matters is the full clinical picture.
PCOS is associated with insulin resistance in the majority of those affected, which drives many of its downstream features including weight gain, metabolic risk, and excess androgen production. It is not purely a reproductive condition.
The Rotterdam Criteria for PCOS Diagnosis
PCOS is diagnosed clinically using the Rotterdam criteria, which require at least 2 of the following 3 features:
Irregular or absent ovulation — usually evidenced by irregular or infrequent periods (oligomenorrhoea or amenorrhoea)
Clinical or biochemical signs of excess androgens — acne, hirsutism, male-pattern hair thinning, or elevated testosterone on blood tests
Polycystic-appearing ovaries on pelvic ultrasound — 12 or more follicles in one ovary, or increased ovarian volume (>10cm³)
Crucially, other causes of irregular periods and elevated androgens (such as thyroid disease, hyperprolactinaemia, and congenital adrenal hyperplasia) must be excluded before a PCOS diagnosis is confirmed.
Symptoms of PCOS
PCOS has a wide spectrum of presentation. Not everyone has the same combination of symptoms, which is part of why diagnosis is frequently delayed.
- Irregular periods: Cycles longer than 35 days, fewer than 8 periods per year, or absent periods altogether. Some women with PCOS have regular periods despite anovulatory cycles.
- Hirsutism: Unwanted coarse hair growth in a male distribution — upper lip, chin, chest, abdomen, lower back. This is the most bothersome androgen-related symptom for many patients.
- Acne: Particularly along the jawline, chin, and lower face — often persisting into adulthood and unresponsive to standard topical treatments.
- Hair thinning: Androgenic alopecia — thinning at the crown and temples rather than diffuse loss.
- Weight gain and difficulty losing weight: Driven by insulin resistance, particularly central or abdominal adiposity.
- Reduced fertility: Irregular or absent ovulation directly impairs conception.
- Mood changes: Depression and anxiety are significantly more prevalent in people with PCOS — this is underrecognised.
Blood Tests for PCOS
A comprehensive hormonal workup for PCOS includes:
- Total testosterone and SHBG — to calculate the free androgen index
- LH and FSH — an elevated LH:FSH ratio is common in PCOS
- AMH (anti-Müllerian hormone) — often significantly elevated in PCOS, reflecting the increased follicle pool
- Oestradiol and progesterone (timed appropriately in the cycle)
- Prolactin — to exclude hyperprolactinaemia as an alternative cause
- Thyroid function — thyroid disorders can mimic or co-exist with PCOS
- Fasting glucose, HbA1c, and fasting insulin — to assess metabolic risk and insulin resistance
- Lipid panel — PCOS carries increased cardiovascular risk
Management Options
Treatment is tailored to the individual's concerns and goals. Lifestyle modification — particularly dietary changes that reduce insulin resistance — has the strongest evidence base and can restore ovulation in some patients. Medical options include the combined oral contraceptive pill (to regulate periods and manage androgen symptoms), anti-androgens for hirsutism and acne, and metformin for metabolic management. Fertility-focused treatment pathways are available where conception is the priority.