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

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women of reproductive age, affecting 8-13% globally — approximately 1 in 10 women worldwide. It is a heterogeneous condition defined by the Rotterdam 2003 consensus criteria, which require 2 of the following 3 features: oligo- or anovulation (infrequent, irregular, or absent menstrual cycles — cycle length above 35 days), clinical or biochemical hyperandrogenism (elevated androgens causing acne, hirsutism, or male-pattern hair loss, or elevated serum testosterone or free androgen index), and polycystic ovarian morphology on ultrasound (12 or more antral follicles per ovary measuring 2-9mm, or total ovarian volume above 10mL). Note that polycystic-appearing ovaries alone, without clinical features, do not constitute PCOS. PCOS is characterised by chronic anovulation driven by abnormal gonadotrophin secretion (elevated LH pulsatility), insulin resistance, and androgen excess — the three core pathophysiological pillars. It is the most common cause of anovulatory infertility and is associated with significant metabolic consequences including type 2 diabetes (4-7x increased risk), cardiovascular disease, endometrial cancer from unopposed oestrogen exposure, and substantial psychological morbidity from the impact on body image, fertility, and chronic illness.

PCOS aetiology is multifactorial, integrating genetic predisposition, insulin resistance, and neuroendocrine dysfunction. Insulin resistance is the central metabolic driver — present in 70-80% of women with PCOS regardless of BMI — causing compensatory hyperinsulinaemia, which synergises with LH to stimulate ovarian theca cell androgen (testosterone and androstenedione) overproduction, simultaneously suppressing hepatic sex hormone-binding globulin (SHBG) production, further elevating free androgen levels. Gonadotrophin dysregulation: increased pulsatile GnRH secretion results in an elevated LH:FSH ratio (above 2:1 in 60% of women with PCOS) — stimulating androgen production by thecal cells while insufficient FSH fails to drive follicular maturation and ovulation, causing multiple small follicles to accumulate in the ovary. Genetic factors: heritability is estimated at 70%; genome-wide association studies have identified variants in LHCGR (LH receptor), FSHR (FSH receptor), INSR (insulin receptor), THADA, and AMH pathway genes as susceptibility loci. Obesity amplifies all three pathophysiological pathways through increased insulin resistance and adipokine secretion, significantly worsening clinical features — but lean women can equally have PCOS, particularly the hyperandrogenic and ovulatory phenotype. Anti-Müllerian hormone (AMH) — produced in excess by the large cohort of small antral follicles — amplifies LH receptor expression and further disrupts folliculogenesis, creating a self-amplifying cycle. Fetal androgen excess and intrauterine programming may contribute to PCOS onset in genetically susceptible daughters of women with PCOS.

Menstrual irregularity is the most common presenting complaint — oligomenorrhea (cycle length above 35 days) or secondary amenorrhea (absence of periods for 3 or more months) from chronic anovulation; in the follicular phenotype, cycles may be regular but anovulatory, detected only on basal temperature charting or LH testing. Hyperandrogenism symptoms: acne — particularly on the jawline, chin, and back (androgen-driven sebaceous gland overactivity), often persisting beyond teenage years; hirsutism — excess terminal hair growth in a male distribution on the upper lip, chin, cheeks, chest, upper abdomen, and inner thighs — quantified using the modified Ferriman-Gallwey score (above 4-6 is clinically significant in South Asian or East Asian populations; above 8 in white or Black populations); androgenic alopecia — temporal recession and vertex thinning. Acanthosis nigricans (dark, velvety, thickened skin in the axillae, nape of neck, and groin folds) signals significant underlying insulin resistance and hyperinsulinaemia. Weight gain: particularly central adiposity with difficulty losing weight despite caloric restriction; even without obesity, central fat distribution is more prevalent in PCOS. Fertility problems arise from chronic anovulation — PCOS is the single most common cause of anovulatory subfertility, accounting for 70-80% of anovulatory infertility. Psychological symptoms are prevalent and frequently undertreated: depression affects 28-35%, anxiety disorders in 35-40%, eating disorders in 10-20%, and reduced health-related quality of life is reported by the majority of women with PCOS regardless of BMI or clinical feature severity.

PCOS is diagnosed by applying Rotterdam 2003 criteria (2 of 3: oligo/anovulation, clinical or biochemical hyperandrogenism, polycystic ovarian morphology on ultrasound), but critically after excluding other causes of hyperandrogenism and menstrual irregularity. Mandatory exclusions: congenital adrenal hyperplasia (17-OH progesterone above 6 nmol/L on Day 3 — requires 250-microgram Synacthen stimulation test); Cushing's syndrome (24-hour urinary free cortisol or 1mg overnight dexamethasone suppression test if clinical features present — hypertension, easy bruising, striae, proximal myopathy); androgen-secreting tumours (very elevated testosterone above 5 nmol/L, rapid virilisation — adrenal and ovarian CT/MRI); hyperprolactinaemia (serum prolactin — galactorrhoea, headache); and thyroid disease (TSH). Blood tests: LH, FSH (elevated LH:FSH ratio above 2:1 in 60%), serum total testosterone, free androgen index (FAI = total testosterone x 100/SHBG); DHEAS (raised in adrenal androgen excess); 17-OH progesterone; AMH (anti-Müllerian hormone — elevated in PCOS reflecting large follicle cohort, increasingly used for diagnosis but not yet in all guidelines); fasting plasma glucose or HbA1c (screen for T2DM); fasting insulin and HOMA-IR (insulin resistance); fasting lipid profile (dyslipidaemia); and SHBG (reduced in insulin resistance — helps calculate FAI). Pelvic ultrasound (transvaginal preferred, transabdominal in sexually inactive women): polycystic ovarian morphology on either or both ovaries using Rotterdam definitions. Endometrial thickness should be assessed in women with amenorrhea exceeding 3 months — endometrial thickness above 10-12mm prompts endometrial biopsy to exclude endometrial hyperplasia or cancer from chronic unopposed oestrogen.

Lifestyle modification is the cornerstone of first-line PCOS management in overweight or obese women: 5-10% body weight loss through dietary modification (caloric deficit of 500 kcal/day, with low glycaemic index diet or Mediterranean dietary pattern showing superior benefits) and 150 minutes of moderate aerobic plus twice-weekly resistance exercise per week significantly restores menstrual regularity and spontaneous ovulation in 30-50%, reduces testosterone and LH levels, improves insulin sensitivity, and reduces cardiometabolic risk — benefits seen even in lean PCOS through improvement of insulin resistance. Menstrual regulation and endometrial protection: combined oral contraceptive pill (COCP) — those with anti-androgenic progestins (co-cyprindiol/Dianette, drospirenone-containing pills — Yasmin, Eloine) are preferred for combined antiandrogen and cycle regulation benefit, reducing hirsutism scores by 30-40% with 6+ months of use; progestogen-only withdrawal bleeds (medroxyprogesterone acetate 10mg daily for 10-12 days every 1-3 months) protect the endometrium in women declining the COCP. Metformin (500-2000mg/day — titrated slowly to reduce gastrointestinal side effects): improves insulin sensitivity, reduces testosterone levels, restores ovulation in 50-60% of women, and reduces T2DM incidence; particularly recommended in women with impaired fasting glucose or pre-diabetes, and as an adjunct to ovulation induction. Hyperandrogenism: topical treatments (benzoyl peroxide, topical retinoids for acne); anti-androgens — spironolactone (50-200mg daily — blocks androgen receptor, reducing hirsutism by 40-70% with 6 months use; requires contraception as teratogenic), finasteride (5-alpha reductase inhibitor, particularly for hair loss); eflornithine cream for facial hirsutism. Ovulation induction for subfertility: letrozole 2.5-5mg daily on days 2-6 of the cycle (aromatase inhibitor — more effective than clomiphene in PCOS per NAVIGATE trial, superior live birth rates 27.5% vs 19.1%); gonadotrophin (FSH) injections with careful dose titration for letrozole-resistant PCOS; IVF with single embryo transfer for women not responding to ovulation induction (risk of ovarian hyperstimulation syndrome — OHSS — with FSH injections requires careful monitoring).

Metabolic complications: type 2 diabetes mellitus risk is 4-7x higher than in unaffected women; 10-year cumulative T2DM incidence of 10-14% in women with PCOS; metabolic syndrome (central adiposity, hypertension, dyslipidaemia, impaired glucose metabolism) in 30-35%. Cardiovascular risk: atherogenic dyslipidaemia (high triglycerides, low HDL, raised small dense LDL), hypertension, and subclinical carotid intima-media thickness increases — long-term cardiovascular mortality data remain reassuring despite intermediate risk markers. Endometrial hyperplasia and endometrial cancer from chronic anovulation: without progesterone to oppose oestrogen, the endometrium undergoes proliferation — endometrial cancer risk is 3-4x higher in women with PCOS, particularly those with prolonged amenorrhea; progestogen (cyclical or as COCP) is required for endometrial protection in any woman with PCOS and amenorrhea or oligomenorrhea. Infertility from chronic anovulation — PCOS accounts for 70-80% of anovulatory infertility. Obstructive sleep apnoea is 5-10x more prevalent in women with PCOS than in age- and BMI-matched controls, driven by androgen effects on pharyngeal muscle tone and adipose distribution. Psychological morbidity: depression (28-35%), anxiety disorders (35-40%), and eating disorders (10-20%) are substantially more prevalent than in women without PCOS, related to the chronic impact on body image, fertility, and symptoms such as unwanted hair growth and acne.

Long-term metabolic monitoring is essential for all women with PCOS throughout their reproductive years and beyond. Annual monitoring: blood pressure, BMI, and waist circumference; HbA1c or fasting glucose every 1-3 years (more frequently with additional diabetes risk factors — obesity, family history); fasting lipid profile; and mental health screening (depression and anxiety questionnaires — PHQ-9, GAD-7). Women with PCOS who are not having regular periods (cycle length above 90 days) should receive endometrial protection with cyclical progestogen (medroxyprogesterone acetate 10mg for 12-14 days every 1-3 months) or the COCP. Regular aerobic exercise (at least 150 minutes weekly) and resistance training improve insulin sensitivity independently of weight loss — a crucial message for lean PCOS. Preconception counselling: achieving a healthy weight before conception significantly reduces gestational diabetes, hypertensive disorders, and miscarriage risk; metformin continuation in early pregnancy reduces miscarriage risk in PCOS (evidence from PROMISE trial and meta-analysis). Psychological support and peer support groups are important for long-term wellbeing given the high prevalence of depression, anxiety, and eating disorders; referral for cognitive behavioural therapy (CBT) or psychological support should be offered at each annual review as needed.

See your GP if you have: fewer than 8 menstrual periods per year or cycles consistently longer than 35 days; excess facial or body hair growth causing distress; acne persisting beyond teenage years, particularly on the jawline or chin; or unexplained weight gain with difficulty losing weight. Seek referral to an endocrinologist or reproductive gynaecologist if: you are trying to conceive and have irregular periods (letrozole ovulation induction is very effective but requires specialist prescription and monitoring); you have been diagnosed with PCOS and have not had a period for more than 3 months (endometrial protection is needed); or you are concerned about symptoms of hyperandrogenism not controlled by the oral contraceptive pill. Seek urgent review for: rapidly progressive hirsutism with deepening voice or clitoromegaly (possible androgen-secreting tumour — very rare but requires urgent workup); amenorrhoea in a young woman with hot flushes (may be premature ovarian insufficiency rather than PCOS). All women with PCOS should have annual metabolic monitoring — type 2 diabetes risk is significantly elevated throughout life.