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

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women of reproductive age, affecting 8-13% of women globally — approximately 116 million women worldwide. It is a heterogeneous condition characterised by the combination of ovulatory dysfunction (irregular or absent periods), clinical or biochemical hyperandrogenism (excess male hormones — causing hirsutism, acne, and hair thinning), and polycystic ovarian morphology (PCOM) on ultrasound (12 or more follicles per ovary or ovarian volume above 10 mL). A diagnosis of PCOS requires two of these three features (Rotterdam criteria, 2003), after exclusion of other causes. PCOS is not merely a reproductive condition — it is associated with significant long-term metabolic risks including Type 2 diabetes, metabolic syndrome, dyslipidaemia, non-alcoholic fatty liver disease, hypertension, and endometrial cancer. It is also strongly associated with depression, anxiety, and impaired quality of life.

The underlying pathophysiology is complex and incompletely understood, involving insulin resistance, excess androgen production, and altered gonadotrophin secretion. Insulin resistance: present in 65-80% of women with PCOS, including non-obese women — hyperinsulinaemia stimulates ovarian theca cell androgen production, exacerbates LH hypersecretion, and reduces sex hormone-binding globulin (SHBG), increasing free androgen levels. Hypothalamic-pituitary dysfunction: elevated LH pulse frequency and amplitude increase the LH:FSH ratio (above 2:1 in many PCOS patients), driving androgen overproduction by ovarian theca cells at the expense of oestrogen synthesis by granulosa cells. Adrenal androgen excess (DHEAS elevation) contributes in 25-30% of patients. Genetic factors: strong familial clustering — first-degree relatives of PCOS women have 20-40% higher risk; candidate genes include DENND1A, FSHR, LHCGR, and THADA. Risk factors: obesity (worsens insulin resistance and androgen excess — though PCOS occurs in non-obese women); intrauterine androgen exposure; early puberty; and low birth weight (associated with insulin resistance).

Menstrual irregularity: oligomenorrhoea (fewer than 9 cycles per year; cycle length above 35 days) or amenorrhoea (absent periods) — the most common presenting complaint. Hyperandrogenism features: hirsutism (excess terminal hair growth on the face, chest, abdomen, and inner thighs — assessed by the modified Ferriman-Gallwey score, with a score above 4-6 being clinically significant); acne (typically inflammatory, on the face, chest, and back); androgenetic alopecia (thinning of scalp hair at the crown — female pattern hair loss). Ovulatory dysfunction: infertility (PCOS is the leading cause of anovulatory infertility, accounting for 80% of cases); recurrent early pregnancy loss. Metabolic features: weight gain (present in 40-80% of women with PCOS), particularly central adiposity; acanthosis nigricans (velvety darkening of skin at the neck and axillae — a marker of insulin resistance); and features of metabolic syndrome (hypertension, dyslipidaemia). Psychological comorbidities: depression (prevalence 30-40% in PCOS — 4 times higher than in women without PCOS) and anxiety are common and frequently undertreated.

Diagnosis uses the Rotterdam criteria (two of three features required): oligo-ovulation or anovulation; clinical or biochemical signs of hyperandrogenism; and polycystic ovarian morphology on ultrasound. Blood tests (biochemical assessment): total testosterone and sex hormone-binding globulin (SHBG) — to calculate free androgen index (FAI = total testosterone x 100/SHBG — elevated above 3.8 in hyperandrogenism); LH and FSH (LH:FSH ratio above 2:1 in some patients); oestradiol; anti-Mullerian hormone (AMH) — markedly elevated in PCOS (above 35 pmol/L), correlating with antral follicle count; prolactin (to exclude hyperprolactinaemia); 17-OHP (to exclude congenital adrenal hyperplasia — a common PCOS mimic); and thyroid function. Exclusion of other causes of androgen excess: late-onset congenital adrenal hyperplasia, Cushing's syndrome, and androgen-secreting tumours (very elevated testosterone above 5 nmol/L should prompt tumour evaluation). Metabolic screening: fasting glucose and HbA1c (or 75g OGTT), fasting lipid profile, and blood pressure — essential in all women with PCOS. Endometrial ultrasound or biopsy: for women with prolonged amenorrhoea (above 3 months) to assess for endometrial hyperplasia.

Treatment is tailored to the patient's primary concern and reproductive goals. Lifestyle modification is first-line for overweight/obese PCOS — a 5-10% weight loss significantly improves cycle regularity (restoring ovulation in 50-60%), reduces androgens, improves insulin sensitivity, and restores fertility. Even modest weight loss is more effective than pharmacological treatment alone. Menstrual cycle regulation and contraception (when fertility not desired): combined oral contraceptive pill (COCP — reduces LH, lowers free androgens, and regulates periods); progestogen-only pill or levonorgestrel-IUS (Mirena) for women in whom oestrogen is contraindicated. Hirsutism and acne: COCP (first-line — particularly those with anti-androgenic progestogens — co-cyprindiol/Dianette, drospirenone); spironolactone (50-200 mg daily — off-label anti-androgen, effective for both hirsutism and acne; requires contraception due to feminisation risk in male fetus); eflornithine cream for facial hirsutism. Insulin sensitisation: metformin (500 mg–2.5 g daily) — reduces insulin resistance, improves cycle regularity, reduces testosterone levels, and may aid weight loss; particularly beneficial in obese PCOS and those with pre-diabetes. Inositol (myo-inositol 2-4 g/day or myo-inositol:D-chiro-inositol 40:1 ratio) — evidence-based supplement improving insulin sensitivity and ovulatory function in PCOS. Ovulation induction for fertility: letrozole (aromatase inhibitor, 2.5-5 mg days 2-6 of cycle) is now first-line (superior to clomiphene — NEJM PPCOSIG trial); clomiphene citrate (50-150 mg days 2-6) alternative; gonadotrophin injections for clomiphene/letrozole failure; laparoscopic ovarian drilling (LOD) for gonadotrophin-resistant PCOS. IVF for patients who fail simpler treatments.

Type 2 diabetes is the most significant metabolic complication of PCOS — women with PCOS have a 5 to 10-fold increased risk of type 2 diabetes compared with age-matched controls, with a 40–50% lifetime cumulative risk; approximately 30–35% of women with PCOS have impaired glucose tolerance and 7–10% have undiagnosed type 2 diabetes at diagnosis. Annual HbA1c or fasting glucose screening is recommended for all women with PCOS. Endometrial cancer risk is elevated 2 to 3-fold from chronic anovulation causing unopposed oestrogen stimulation of the endometrium without progesterone protection — irregular periods (less than 4 cycles per year) for more than 2 years are an indication for endometrial biopsy. Cardiovascular disease: PCOS confers a substantially elevated risk of hypertension, dyslipidaemia (low HDL, elevated triglycerides and small dense LDL), metabolic syndrome, and subclinical atherosclerosis. Long-term cardiovascular mortality data are conflicting but the intermediate risk markers (carotid intima-media thickness, coronary artery calcium scoring) are consistently elevated. Obstructive sleep apnoea (OSA) affects 30–35% of women with PCOS and 70–80% of obese women with PCOS — 30-fold increased prevalence compared with BMI-matched controls — contributing to insulin resistance and cardiovascular risk. Non-alcoholic fatty liver disease (NAFLD) affects up to 40% of women with PCOS and is associated with insulin resistance independent of BMI. Infertility from chronic anovulation — the most common symptom-driven complication causing patients to seek care — is treatable in most cases with ovulation induction. Psychological complications including depression (4-fold elevated risk), anxiety, poor body image, and reduced quality of life from hirsutism and irregular periods affect the majority of women with PCOS.

There is no established prevention for PCOS itself. Prevention of long-term complications requires a proactive approach. Endometrial cancer risk: women with PCOS are 2-6 times more likely to develop endometrial cancer due to chronic unopposed oestrogen exposure from anovulation. All women with PCOS should have withdrawal bleeds at least every 3-4 months — using a COCP, progestogen therapy, or IUS ensures adequate endometrial protection. Type 2 diabetes prevention: screening with HbA1c or OGTT every 1-3 years; lifestyle modification in those with impaired fasting glucose. Cardiovascular risk reduction: treat hypertension, dyslipidaemia, and obesity; regular physical activity (150 minutes of moderate exercise per week reduces insulin resistance and improves mental health). Mental health: PCOS has the highest prevalence of depression and anxiety of any gynaecological condition — routine psychological screening and access to CBT and peer support groups should be part of PCOS care.

See a GP or gynaecologist if you have: irregular periods (fewer than 8 cycles per year, or cycles consistently above 35 days); absent periods for more than 3 months (not due to pregnancy); unwanted hair growth on the face, chest, or abdomen; acne that is not responding to standard skin treatments; difficulty conceiving after 12 months of regular unprotected intercourse (or 6 months if over 35); or unexplained weight gain with central obesity. All women with PCOS should have metabolic screening (blood glucose, lipids, blood pressure) at diagnosis and every 1-3 years thereafter. If you have PCOS and experience irregular bleeding, spotting between periods, or particularly heavy periods, seek urgent gynaecological review to assess the endometrium.