PCOS (Polycystic Ovary Syndrome) — Causes, Symptoms & Treatment Guide — Symptoms, Causes & Treatment | MyMedicPlus

Polycystic ovary syndrome (PCOS) is a complex, heterogeneous endocrine and metabolic disorder affecting 8-13% of reproductive-age women — the most common hormonal disorder in women of reproductive age, affecting approximately 116 million women worldwide. It is characterised by a combination of ovarian dysfunction (oligo/anovulation), androgen excess (hyperandrogenism — clinical and/or biochemical), and polycystic ovarian morphology (PCOM) on ultrasound. Diagnosis requires at least 2 of 3 Rotterdam criteria: irregular/absent periods, clinical or biochemical hyperandrogenism, and polycystic ovaries on ultrasound. PCOS has significant short-term effects (irregular periods, acne, hirsutism, infertility) and long-term metabolic consequences (type 2 diabetes risk up to 7x higher, cardiovascular disease risk, endometrial cancer risk from chronic unopposed oestrogen exposure due to anovulation). Up to 70% of women with PCOS remain undiagnosed globally. The condition has no known cure but is effectively managed through lifestyle modification, hormonal contraception, insulin sensitisers such as metformin, inositol supplementation, and targeted fertility treatment including clomifene or letrozole for ovulation induction.

PCOS is a multifactorial condition with genetic and environmental determinants. The central pathophysiological mechanisms are: Insulin resistance (present in 70-80% of women with PCOS, regardless of body weight) — hyperinsulinaemia drives excess androgen production by theca cells in the ovary (insulin potentiates LH-stimulated androgen synthesis); high androgens impair follicular development and cause anovulation; insulin resistance also impairs glucose-stimulated insulin secretion, increasing type 2 diabetes risk. Hypothalamic-pituitary dysfunction: increased frequency of GnRH pulses preferentially stimulates LH over FSH secretion, leading to elevated LH:FSH ratio — LH excess drives androgen production; reduced FSH impairs follicular maturation and ovulation. Genetic factors: strong family history — sisters of PCOS patients have 30-50% prevalence; multiple susceptibility genes identified (LHCGR, FSHR, INSR, THADA). Adipokine dysregulation in obesity worsens insulin resistance and androgen excess — obesity is a major exacerbating factor (but PCOS also occurs in lean women). Intrauterine androgen exposure may predispose daughters of PCOS mothers to the condition.

Menstrual irregularity: oligomenorrhoea (cycles longer than 35 days) or amenorrhoea (absent periods for 3+ months) — due to anovulation; cycle length varies widely; some women have regular cycles but still have anovulatory cycles (ovulatory PCOS). Hyperandrogenism symptoms: hirsutism (excess hair in androgen-sensitive distribution — upper lip, chin, jaw, chest, abdomen, inner thighs — Ferriman-Gallwey score above 4-6), acne (typically inflammatory, jawline distribution, persistent beyond adolescence), androgenic alopecia (female-pattern hair loss — frontal/vertex thinning). Weight and metabolic features: weight gain (50-80% of PCOS women are overweight or obese — excess weight amplifies all PCOS features; though lean PCOS also occurs), acanthosis nigricans (velvety, darkened skin in armpits, neck creases, groin — marker of insulin resistance), skin tags. Fertility: subfertility or infertility due to anovulation — the most common cause of anovulatory infertility. Psychological: depression and anxiety are significantly more prevalent in PCOS (2-3x higher risk) — driven by symptom burden, body image concerns, and the chronic nature of the condition.

Rotterdam criteria (2003, revised 2023 International PCOS Guideline): diagnosis requires at least 2 of 3 criteria: (1) Oligo/anovulation (irregular periods — cycles consistently more than 35 days, or fewer than 8 cycles per year); (2) Clinical hyperandrogenism (hirsutism, acne, androgenic alopecia) or biochemical hyperandrogenism (elevated total testosterone, free androgen index, or DHEAS); (3) Polycystic ovarian morphology (PCOM) on transvaginal ultrasound — 20 or more follicles per ovary (2023 threshold) and/or ovarian volume above 10 cm^3. Exclusions required (diagnoses to rule out before confirming PCOS): thyroid dysfunction (TSH), hyperprolactinaemia (prolactin), non-classical congenital adrenal hyperplasia (17-OH progesterone in follicular phase — elevated above 6 nmol/L warrants ACTH stimulation test), Cushing's syndrome (if suspected), and androgen-secreting tumour (testosterone above 5 nmol/L warrants urgent investigation). Blood tests: LH, FSH (elevated LH:FSH ratio, typically >2:1 — supportive but not diagnostic), testosterone (total and free/FAI), DHEAS, sex hormone binding globulin (SHBG — low in hyperandrogenism). Metabolic assessment: fasting glucose and insulin (HOMA-IR for insulin resistance), HbA1c, fasting lipid profile. BMI and waist circumference measurement. Transvaginal ultrasound: gold standard for PCOM assessment.

Treatment is tailored to the patient's primary concerns: menstrual regulation, hyperandrogenism management, fertility, or metabolic risk reduction. Lifestyle modification is the most effective intervention for overweight/obese PCOS: weight loss of 5-10% improves menstrual regularity (50-90%), reduces androgen levels, restores ovulation, and reduces insulin resistance and metabolic risk. Dietary approaches: Mediterranean diet, low glycaemic index diet, and calorie deficit — all are effective. Menstrual regulation (in women not seeking pregnancy): Combined Oral Contraceptive Pill (COCP) — first-line; regulates cycles, reduces androgen production and bioavailability (oestrogen increases SHBG), reduces hirsutism and acne (anti-androgenic pill choices: Yasmin/Yaz — drospirenone; Belara — chlormadinone); protects against endometrial hyperplasia from chronic anovulation. Cyclic progestogens (medroxyprogesterone acetate 10mg days 1-12 monthly) if COCP contraindicated — to prevent endometrial hyperplasia. Hyperandrogenism (hirsutism/acne): COCP is first-line; add anti-androgen: spironolactone (50-200mg) — if pregnancy not planned; cyproterone acetate (used in some countries). Topical eflornithine cream for facial hirsutism. Laser/IPL hair removal for established hirsutism. Metformin: reduces insulin resistance; modestly improves menstrual regularity; synergistic with lifestyle change; recommended for metabolic risk reduction and as adjunct to ovulation induction. Inositol (myo-inositol 4g daily + D-chiro-inositol): insulin sensitiser; improves menstrual regularity and oocyte quality; well-tolerated; increasingly recommended in international guidelines. Fertility (ovulation induction): letrozole (2.5-7.5mg days 2-6) is now first-line (superior to clomifene — higher live birth rate, lower multiple pregnancy risk); clomifene (50-150mg days 2-6) — second-line; gonadotrophins (FSH injections) — for clomifene/letrozole-resistant PCOS; laparoscopic ovarian drilling (LOD) — surgical alternative for gonadotrophin-resistant anovulation; IVF — if ovulation induction fails.

Type 2 diabetes (30-40% of women with PCOS have impaired glucose tolerance by their 30s; 5-7 fold higher lifetime risk than the general population — annual HbA1c and fasting glucose screening is mandatory). Endometrial hyperplasia and cancer (chronic anovulation causes unopposed oestrogen stimulation of the endometrium — endometrial cancer risk is 3-fold higher in untreated PCOS; cyclical progestogens or COCP are essential for endometrial protection in all anovulatory women). Cardiovascular disease (dyslipidaemia — elevated triglycerides, low HDL — hypertension, and metabolic syndrome are significantly more prevalent; long-term cardiovascular event risk is elevated, particularly in obese women with insulin resistance). Anovulatory infertility (PCOS is the most common cause of anovulatory infertility worldwide — affecting the majority of women with PCOS who attempt conception; ovulation induction is required). Psychological complications (depression affects 2-3 times more women with PCOS than controls; anxiety, disordered eating, poor body image — screening at every clinical review is recommended). Obstructive sleep apnoea (risk 5-10 times higher in PCOS — from obesity and androgen excess).

PCOS cannot be prevented, but symptoms and long-term complications can be significantly managed. Weight maintenance in a healthy range (BMI 18.5-24.9) is the most important modifiable factor — even modest weight gain worsens all PCOS features. Regular aerobic and resistance exercise (150+ minutes per week) independently improves insulin sensitivity, reduces androgen levels, and improves menstrual regularity regardless of weight change. Low glycaemic index (low GI) diet: reduces insulin spikes and has been shown to improve menstrual regularity and metabolic parameters in PCOS. Annual metabolic screening in all women with PCOS: fasting glucose and HbA1c (for diabetes detection — PCOS women have 7x higher type 2 diabetes risk), lipid profile (dyslipidaemia common), blood pressure. Endometrial protection: women with irregular periods must be treated with COCP or cyclical progestogens to prevent endometrial hyperplasia from unopposed oestrogen exposure — risk of endometrial cancer is 3x higher in untreated PCOS. Psychological support: mental health screening with PHQ-9 and GAD-7 at every PCOS review; CBT, mindfulness, and peer support groups address the significant mood comorbidity.

See your GP or a gynaecologist if you have: irregular or absent periods (fewer than 8 periods per year or cycles consistently more than 35 days), unwanted hair growth on the face, chest, or abdomen, persistent acne beyond adolescence (particularly jawline pattern), difficulty conceiving after 12 months of trying (or 6 months if aged 35+), unexplained weight gain particularly around the waist, or any combination of these features. PCOS is frequently diagnosed late — many women are undiagnosed for years. Do not wait or assume these symptoms are 'normal'. Early diagnosis enables timely treatment to manage symptoms, protect fertility, and prevent long-term complications including diabetes and endometrial cancer. Seek genetic counselling or early assessment if you have a first-degree relative with PCOS — you have a 30-50% probability of also having the condition.