Polycystic Ovary Syndrome: A Hormonal and Metabolic Disorder

Polycystic ovary syndrome is a chronic hormonal, reproductive and metabolic disorder. It can disrupt ovulation, increase androgen activity and affect periods, fertility, skin, hair and long term metabolic health. Diagnosis requires a characteristic adult feature pattern after alternative causes are excluded, while treatment addresses current priorities and future health.

What PCOS is Polycystic ovary syndrome is a chronic hormonal, reproductive and metabolic disorder affecting ovarian function and several body systems. It can alter ovulation, androgen activity, menstrual cycles, fertility, glucose regulation, skin and hair growth. The condition varies widely, so two people with PCOS may have very different symptoms and long term risks. There is no single test that confirms PCOS in every person. A newer name is being introduced In May 2026, international organisations introduced the name polyendocrine metabolic ovarian syndrome, shortened to PMOS. The newer name reflects that the disorder affects more than the ovaries and does not require ovarian cysts. PCOS remains widely recognised in clinical records, research and public information, so this lesson uses the familiar term. The diagnostic and management principles described here remain based on current international guidance. How common PCOS is PCOS affects an estimated ten to thirteen percent of reproductive aged women worldwide. Many remain undiagnosed because symptoms vary, access differs and irregular periods can be normalised. The condition often runs in families, reflecting genetic susceptibility interacting with metabolic and environmental influences. A family history of PCOS or type 2 diabetes can increase clinical suspicion without determining diagnosis. The ovaries do not contain dangerous cysts The word polycystic can be misleading because the ultrasound appearance usually represents many small developing follicles. Follicles are fluid filled structures containing immature eggs, not pathological cysts requiring surgical removal. Some people with PCOS have this ovarian appearance, while others have normal looking ovaries. Polycystic ovarian morphology alone does not establish the diagnosis. How normal ovulation works During a typical cycle, several ovarian follicles begin developing under hormonal signals from the brain and ovaries. Usually one follicle becomes dominant, releases an egg and then produces progesterone after ovulation. Progesterone helps organise and stabilise the womb lining before the next menstrual bleed. In PCOS, follicle development can stall before regular ovulation occurs. Insulin resistance Insulin resistance means body tissues respond less effectively to insulin, which regulates blood glucose and energy storage. The pancreas may compensate by releasing more insulin, creating higher circulating insulin concentrations. Insulin resistance is an important mechanism in PCOS, although its degree varies and can occur at any body size. Routine fasting insulin measurements are not recommended because available tests do not guide care reliably. How insulin affects androgen production Higher insulin concentrations can stimulate ovarian theca cells to produce more androgens. Insulin can also reduce liver production of sex hormone binding globulin, leaving more biologically active testosterone available. These effects can contribute to hirsutism, acne, scalp hair thinning and disrupted follicle development. Insulin resistance therefore connects reproductive and metabolic features without explaining every case alone. Androgens in PCOS Androgens include testosterone and related hormones produced by the ovaries and adrenal glands. Everyone produces androgens, but excessive activity can alter hair follicles, skin oil production and ovulation. Hyperandrogenism can be clinical, biochemical or both. Clinical hyperandrogenism is visible through features such as hirsutism, while biochemical hyperandrogenism is detected through blood testing. Altered ovarian signalling Changes in communication between the hypothalamus, pituitary gland and ovaries can favour increased luteinising hormone activity. This can support androgen production and reduce coordinated follicle maturation in susceptible people. The hormonal pattern is variable and should not be diagnosed from an LH to FSH ratio. PCOS develops through interacting genetic, metabolic, hormonal and environmental influences rather than one simple imbalance. The Rotterdam diagnostic framework In adults, PCOS is diagnosed when at least two of three recognised features are present after excluding alternative causes. The three features are ovulatory dysfunction, clinical or biochemical hyperandrogenism, and polycystic ovarian morphology. This is commonly called the revised Rotterdam framework. A person does not need all three features, so several different PCOS phenotypes exist. Criterion one: ovulatory dysfunction Ovulatory dysfunction includes infrequent ovulation, absent ovulation or menstrual cycles suggesting these patterns. Oligomenorrhoea usually means menstrual cycles occurring less often than expected. Amenorrhoea means menstruation has stopped for a prolonged interval or has not begun by the expected age. Regular bleeding does not always prove ovulation, so progesterone testing can occasionally clarify uncertain cases. Defining irregular cycles Menstrual irregularity must be interpreted according to time since the first menstrual period. During the first year after menarche, irregular cycles commonly reflect normal pubertal development. More than three years after menarche, cycles shorter than 21 days, longer than 35 days or fewer than eight yearly are irregular. Any single cycle exceeding 90 days more than one year after menarche also warrants assessment. Criterion two: hyperandrogenism Clinical hyperandrogenism can present through hirsutism, persistent acne or female pattern scalp hair thinning. Hirsutism is the strongest visible predictor of androgen excess in adults. Acne or scalp hair thinning alone is less specific because many other factors can cause them. Biochemical testing is most helpful when visible signs are minimal, uncertain or changing rapidly. Measuring androgens Total testosterone and calculated free testosterone are the preferred initial biochemical assessments. Androstenedione or DHEAS can be considered when testosterone results are normal but suspicion remains. Results depend heavily on laboratory methods, reference ranges, age and hormonal treatment. Combined hormonal contraception alters androgen measurements, making interpretation difficult during treatment. Criterion three: polycystic ovarian morphology Ultrasound can identify increased follicle numbers or ovarian volume meeting adult morphology thresholds. The exact thresholds depend on scanning equipment, probe frequency and the guideline used by the imaging service. A skilled transvaginal scan usually provides the clearest adult ovarian images when acceptable and suitable. An abdominal scan can be used when internal scanning is declined or inappropriate, although resolution may be lower. When ultrasound is unnecessary Adults with both irregular cycles and hyperandrogenism already meet two Rotterdam features after exclusions. Ultrasound is not required merely to confirm a third feature in this situation. Avoiding unnecessary scanning reduces delay, cost and confusion about harmless follicle appearances. Imaging may still be appropriate for pelvic pain, abnormal bleeding or another suspected condition. Anti Müllerian hormone The 2023 international guideline allows a validated anti Müllerian hormone test as an alternative to ultrasound for adult ovarian morphology. AMH must not be used as the only diagnostic test for PCOS. Assays and thresholds vary, and age, contraception and other factors affect interpretation. AMH is not recommended for diagnosing PCOS during adolescence. PCOS is a diagnosis of exclusion The Rotterdam features overlap with several endocrine, reproductive and medication related conditions. Clinicians therefore exclude important alternatives before confirming PCOS. The exact investigation plan depends on menstrual history, examination, androgen severity and pregnancy possibility. A diagnosis should not be made from an ultrasound report alone. Common conditions to exclude Pregnancy is excluded whenever it is possible and menstruation is delayed or absent. Thyroid disease and hyperprolactinaemia can disrupt menstrual cycles and require blood testing when PCOS is assessed. Non classic congenital adrenal hyperplasia can cause androgen excess and is screened using 17 hydroxyprogesterone. Clinical features may also require assessment for Cushing syndrome, hypothalamic amenorrhoea or primary ovarian insufficiency. Hypothalamic amenorrhoea Low energy availability, substantial weight loss, intense exercise or major stress can suppress hypothalamic reproductive signalling. Periods may become infrequent or stop, often with low oestrogen and low or normal gonadotrophins. This pattern requires nutritional, bone health and broader medical assessment rather than automatic PCOS treatment. Some people can have overlapping metabolic or androgen features, making specialist interpretation necessary. Primary ovarian insufficiency Primary ovarian insufficiency involves reduced ovarian function before age 40. It can cause absent periods, hot flushes, vaginal dryness and raised follicle stimulating hormone levels. The long term bone, cardiovascular and fertility implications differ substantially from PCOS. Testing is guided by the history and should not be delayed when symptoms suggest oestrogen deficiency. Cushing syndrome Cushing syndrome results from prolonged excessive cortisol exposure. Possible clues include easy bruising, wide purple stretch marks, proximal muscle weakness and difficult hypertension or diabetes. Weight gain and irregular periods alone are not sufficient to suggest Cushing syndrome. Targeted endocrine testing is appropriate when the broader clinical pattern is present. Adolescents require a stricter approach Normal puberty commonly causes irregular cycles, acne and multifollicular ovarian appearances. Using adult Rotterdam criteria without adjustment can overdiagnose a normal developmental stage. Current guidance requires both persistent ovulatory dysfunction and hyperandrogenism for adolescent diagnosis after excluding alternatives. Young people with incomplete features can be described as having increased risk and reassessed later. Ultrasound in adolescents Pelvic ultrasound is not recommended for diagnosing PCOS within eight years after menarche. Multifollicular ovaries are common during normal adolescence and have poor diagnostic specificity. Ovarian morphology should therefore not be used as a standalone criterion in this age group. AMH is also unsuitable for adolescent diagnosis because normal developmental overlap remains substantial. Menstrual features PCOS can cause long cycles, unpredictable periods, very light bleeding or complete absence of menstruation. Some people experience occasional heavy withdrawal bleeding after the womb lining has accumulated for several months. Irregular bleeding still requires assessment for pregnancy, contraception effects and other gynaecological causes. PCOS does not explain every abnormal bleeding pattern automatically. Hirsutism Hirsutism means coarse terminal hair growing in androgen sensitive areas. Common sites include the face, chest, lower abdomen, back and inner thighs. Hair growth patterns vary by ethnicity, age, genetics and personal grooming practices. Assessment should focus on change, distress and rapid progression rather than imposing one cultural standard. Acne Androgen activity can increase sebum production and contribute to persistent inflammatory acne. Acne alone is a relatively weak predictor of biochemical hyperandrogenism, especially during adolescence. Standard topical and systemic acne treatments remain appropriate alongside PCOS management. Rapid acne progression with virilisation requires investigation for a more severe androgen source. Androgenic alopecia Female pattern hair loss usually causes thinning across the crown while preserving the frontal hairline. PCOS can contribute through androgen sensitivity, but iron deficiency, thyroid disease and genetic factors also matter. Hair loss can have substantial psychological impact even when other PCOS symptoms are mild. Dermatology assessment may be useful when the diagnosis or treatment response remains uncertain. Fertility and anovulation PCOS is a leading cause of anovulatory infertility because eggs are released irregularly or not released. Infrequent ovulation reduces the number of opportunities for conception. Many people with PCOS conceive naturally, while others need lifestyle, ovulation induction or assisted conception support. PCOS does not mean pregnancy is impossible. Other fertility factors still matter A PCOS diagnosis should not prevent assessment of semen, tubal patency, age and other reproductive factors. Ovulation induction cannot overcome blocked tubes or a major sperm related fertility problem. The timing of investigations is individualised according to history and proposed treatment complexity. Fertility care should avoid assuming that body weight or PCOS alone explains every delay. Central adiposity and weight Higher weight and central adiposity are common in PCOS but are not required for diagnosis. PCOS can occur in people across the full range of body sizes. Central adiposity can worsen insulin resistance, androgen activity and cardiometabolic risk. Weight should be discussed with permission, clinical purpose and avoidance of blame or stigma. Type 2 diabetes risk PCOS increases the risk of impaired glucose tolerance and type 2 diabetes regardless of age or body mass index. The international guideline recommends glycaemic assessment at diagnosis and repeated assessment every one to three years. A 75 gram oral glucose tolerance test is the most accurate assessment in PCOS. Fasting glucose or HbA1c can be used when an OGTT is impractical, while recognising reduced sensitivity. Cardiovascular risk factors PCOS is associated with higher rates of dyslipidaemia, hypertension, insulin resistance and other cardiovascular risk factors. Overall cardiovascular event risk remains low for many younger premenopausal people, but prevention still matters. A lipid profile is recommended at diagnosis, with later testing guided by results and individual risks. Blood pressure should be measured annually and during pregnancy or fertility planning. Obstructive sleep apnoea Obstructive sleep apnoea occurs more frequently in PCOS, even after accounting for body mass index. Clues include loud snoring, waking unrefreshed, morning headaches, daytime sleepiness and persistent fatigue. A screening questionnaire can identify who needs formal sleep assessment. Diagnosis requires an appropriate sleep study rather than symptoms alone. Fatty liver disease PCOS is associated with metabolic dysfunction associated steatotic liver disease, previously called non alcoholic fatty liver disease. Risk is higher when insulin resistance, type 2 diabetes, dyslipidaemia or central adiposity is present. PCOS alone does not prove liver disease, and routine imaging is not required for every person. Abnormal liver tests or metabolic risk factors should prompt assessment under appropriate liver pathways. Endometrial hyperplasia and cancer Long standing anovulation can expose the womb lining to oestrogen without regular progesterone opposition. The lining may become excessively thick, a condition called endometrial hyperplasia. Premenopausal people with PCOS have a higher relative risk of endometrial hyperplasia and endometrial cancer. The overall absolute chance remains low, so routine cancer screening is not recommended without clinical indications. Why regular endometrial protection matters Progesterone after ovulation normally limits growth and organises shedding of the womb lining. When ovulation is infrequent, months can pass without this protective progesterone exposure. Cycle regulation or regular progestogen treatment reduces prolonged unopposed oestrogen stimulation. Endometrial protection matters even when contraception or pregnancy is not the person's current priority. Long gaps without bleeding A cycle lasting more than 90 days warrants pregnancy testing and clinical advice. The clinician may recommend a short cyclical progestogen course to trigger a withdrawal bleed. Hormonal contraception or a progestogen releasing intrauterine system can provide ongoing protection for suitable people. Persistent abnormal bleeding or excessive endometrial thickness can require ultrasound, biopsy or gynaecology assessment. Endometrial protection does not require monthly bleeding Some hormonal methods keep the womb lining thin while producing very light bleeding or no bleeding. Absence of withdrawal bleeding during an appropriate progestogen containing method is not the same as untreated anovulation. The protective mechanism depends on endometrial progestogen exposure rather than visible monthly bleeding. Unexpected new bleeding still requires review according to age, pattern and risk factors. Psychological and quality of life impact Irregular periods, hirsutism, acne, scalp hair loss and fertility uncertainty can affect self esteem and body image. Depression and anxiety symptoms occur more commonly among adults and adolescents with PCOS. Disordered eating can occur at any body size and deserves sensitive assessment. Treatment priorities should reflect the person's concerns rather than assuming weight or fertility matters most. Weight stigma People with PCOS frequently encounter blame and oversimplified advice about body weight. Weight stigma can delay care, worsen psychological distress and discourage future healthcare contact. Healthy lifestyle support should be available at every body size and should not depend on achieving weight loss. Clinicians should ask permission before weighing and explain how the information will guide care. Clinical assessment Assessment begins with menstrual history, age at menarche and the duration and pattern of irregularity. The clinician asks about hair growth, acne, scalp hair loss, weight change, medicines and pregnancy plans. Examination can assess blood pressure, body composition, hirsutism, acne, alopecia and signs of insulin resistance. The person should be examined respectfully, with permission for sensitive observations and measurements. Acanthosis nigricans Acanthosis nigricans causes darker, thickened, velvety skin, commonly around the neck, armpits or groin. It can indicate substantial insulin resistance but is not specific to PCOS. Rapid severe insulin resistance signs may require specialist assessment for rarer metabolic disorders. Skin appearance should be described neutrally without implying poor hygiene. Initial blood tests Typical exclusion testing includes pregnancy testing, thyroid stimulating hormone, prolactin and 17 hydroxyprogesterone. Total and free testosterone assess biochemical hyperandrogenism when required. Further tests can include DHEAS, androstenedione, gonadotrophins or cortisol investigations according to clinical features. Testing should be targeted rather than using one identical panel for everyone. Rapid virilisation is not typical PCOS Virilisation means more pronounced androgen effects beyond ordinary hirsutism or acne. Features include voice deepening, marked clitoral enlargement, rapidly increasing muscle mass and rapidly progressive coarse hair. Rapid onset over months or markedly abnormal androgen results raise concern about an ovarian or adrenal tumour. This requires urgent specialist investigation rather than routine PCOS management. Lifestyle management Healthy eating, physical activity and behavioural support are core treatments throughout life with PCOS. Benefits include improved metabolic health, fitness, sleep, quality of life and prevention of excess weight gain. No single PCOS diet has proven superiority over other sustainable balanced dietary patterns. Plans should be realistic, culturally appropriate and adapted to disability, finances and personal preferences. Benefits without weight loss Exercise and healthy eating can improve glucose regulation, lipids, fitness and wellbeing without changing body weight. This is important because weight loss is not required to validate effort or receive treatment. People who are not at higher weight should focus on health maintenance and prevention of excess gain. Lifestyle treatment should not replace indicated medication, fertility care or endometrial protection. Modest weight loss and ovulation For people with higher weight who choose intentional weight loss, modest loss can improve insulin sensitivity and menstrual regularity. A reduction around five to ten percent can restore ovulation in some people, but not everyone. Pressure to delay all fertility treatment until a target weight is reached can cause harmful delay. Age, metabolic health and local treatment criteria should be discussed transparently. Combined hormonal contraception A combined oral contraceptive can regulate bleeding, protect the endometrium and improve hirsutism or acne. Lower oestrogen preparations are generally preferred when suitable, using standard contraceptive eligibility guidance. Potential risks include venous thrombosis, blood pressure effects and medicine specific adverse effects. The method prevents pregnancy while used and does not treat infertility directly. Cyclical progestogen A short progestogen course can be prescribed every few months to produce endometrial shedding. This is useful when oestrogen containing contraception is unsuitable or unwanted. Cyclical progestogen protects the womb lining but may not improve hirsutism or acne. The regimen and need for pregnancy testing should be explained clearly. Progestogen only options Progestogen only pills, implants, injections or an intrauterine system can provide contraception and endometrial protection. Bleeding patterns vary and can include irregular bleeding or complete absence of bleeding. The levonorgestrel intrauterine system keeps the endometrium thin and often reduces heavy bleeding. Individual suitability depends on medical history, preferences and reproductive plans. Metformin Metformin improves insulin action and is used primarily for metabolic features of PCOS. It is particularly considered in adults with higher metabolic risk, impaired glucose regulation or body mass index above 25. Metformin can also improve cycle regularity, although combined contraception is generally more effective for hirsutism and bleeding control. It does not replace endometrial protection when long gaps without bleeding continue. Metformin safety and expectations Common adverse effects include nausea, abdominal discomfort and diarrhoea, especially when treatment begins quickly. Starting with a low dose and increasing gradually can improve tolerance. Long term treatment can lower vitamin B12 in susceptible people, so monitoring may be appropriate. Metformin is not an instant fertility treatment or a guaranteed weight loss medicine. Treating hirsutism Treatment choices include cosmetic removal, combined contraception and selected anti androgen medicines. Shaving, threading, waxing, electrolysis and laser treatment do not make hair grow back thicker. Laser works best for some hair and skin combinations and requires appropriately trained practitioners. Meaningful medication related hair improvement usually takes at least six months because hair cycles change slowly. Co cyprindiol Co cyprindiol combines ethinylestradiol with low dose cyproterone acetate and has anti androgen effects. International guidance places this behind lower risk combined pills because venous thromboembolism risk is higher. UK use is generally reserved for severe acne or moderately severe hirsutism when other treatments are inadequate. It should not be combined with another hormonal contraceptive and requires individual thrombosis risk assessment. Spironolactone Spironolactone blocks androgen effects and can reduce hirsutism or acne when first line approaches are insufficient. It is generally considered after at least six months of combined contraception or cosmetic treatment, or when those options are unsuitable. Treatment is off label for these symptoms in the United Kingdom and requires discussion of benefits and uncertainties. Kidney function, potassium risk, blood pressure and interacting medicines influence safe prescribing. Anti androgens and pregnancy prevention Anti androgens can interfere with development of external genital structures in a male fetus. Effective contraception is therefore required whenever pregnancy is possible during treatment. Spironolactone should be stopped and reviewed before attempting conception. Anti androgens should not be prescribed casually for rapid virilisation before a tumour has been excluded. Acne management Acne treatment can include topical retinoids, benzoyl peroxide, antibiotics and hormonal options according to severity. Combined hormonal contraception can improve androgen related acne when medically suitable. Spironolactone is a specialist or experienced prescriber option for persistent adult female acne. Pregnancy intentions matter because topical retinoids and anti androgens are unsuitable during pregnancy. Fertility assessment Fertility treatment begins after confirming that anovulation is the principal problem and assessing other possible factors. Preconception care includes folic acid, blood pressure, glucose status, medicines, smoking, alcohol and emotional wellbeing. An oral glucose tolerance test is recommended when planning pregnancy or fertility treatment. Pregnancy should be excluded before ovulation induction medicines are started. Letrozole Letrozole is the international guideline's first line medicine for anovulatory infertility due to PCOS without other infertility factors. It temporarily reduces oestrogen production, encouraging the pituitary gland to stimulate follicle development. Letrozole improves ovulation, pregnancy and live birth outcomes compared with clomifene in this setting. Use for ovulation induction remains off label in some countries, including aspects of UK practice, requiring informed discussion. Clomifene citrate Clomifene is an alternative oral ovulation induction medicine when letrozole is unavailable, unsuitable or not permitted. It blocks oestrogen feedback at the hypothalamus, increasing signals that stimulate ovarian follicles. Clomifene increases multiple pregnancy risk and may require ultrasound monitoring. Treatment is limited to specialist supervised courses rather than continued indefinitely. Metformin in fertility treatment Metformin can improve ovulation and pregnancy outcomes but is less effective alone than letrozole or clomifene. It can be combined with clomifene in selected people to improve ovulation or pregnancy outcomes. The greatest role is often in people with metabolic risk or resistance to initial oral induction. Gastrointestinal adverse effects and the availability of more effective ovulation medicines should be discussed. Gonadotrophins Gonadotrophin injections directly stimulate ovarian follicle development and are generally second line treatment after oral induction fails. They require specialist expertise and frequent ultrasound monitoring. Excessive response can cause multiple pregnancy or ovarian hyperstimulation syndrome. Low dose step up protocols aim to develop one follicle while reducing these risks. Laparoscopic ovarian surgery Laparoscopic ovarian surgery, sometimes called ovarian drilling, is a second line option in selected resistant anovulatory infertility. It can reduce ovarian androgen production and support ovulation without repeated injection cycles. Surgical, anaesthetic and adhesion risks must be weighed against gonadotrophin treatment. It is not a treatment for polycystic ovarian morphology alone. In vitro fertilisation IVF is generally considered after first line and second line ovulation treatments fail, unless another indication requires earlier use. Ovarian stimulation protocols are adjusted because PCOS increases ovarian hyperstimulation risk. Single embryo transfer can reduce multiple pregnancy risk when clinically appropriate. Many people with PCOS achieve successful pregnancy naturally or with assisted treatment. Pregnancy risks PCOS is associated with increased risks of gestational diabetes, hypertension, pre eclampsia and preterm birth. Preconception metabolic optimisation and early antenatal assessment can reduce avoidable risk. Metformin during pregnancy has not been shown to prevent gestational diabetes or pre eclampsia routinely. Pregnancy management should follow obstetric guidance rather than assuming metformin must always continue. Cardiometabolic follow up PCOS management continues beyond controlling periods or achieving pregnancy. Blood pressure, glucose status, lipids, sleep symptoms and lifestyle factors require periodic review. Monitoring frequency depends on age, results, medication, pregnancy plans and additional risk factors. Routine insulin measurements are unnecessary despite insulin resistance being central to the disorder. When referral is appropriate Endocrinology or gynaecology referral is appropriate when diagnosis remains uncertain or androgen levels are markedly elevated. Fertility services manage ovulation induction, gonadotrophins and assisted conception. Dermatology can help with severe acne, alopecia or difficult hirsutism. Sleep, liver, metabolic and psychological services may be needed according to associated conditions. Red flag androgen symptoms Slowly developing hirsutism over several years can fit PCOS, especially with irregular cycles. Rapid progression over months, voice deepening or marked clitoral enlargement is not typical. A new pelvic or abdominal mass, severe androgen elevation or virilisation requires urgent tumour exclusion. Normal or moderately raised androgen results do not fully exclude a tumour when progression is clinically rapid. The central safety message PCOS requires two adult diagnostic features after alternative causes have been excluded. Ultrasound morphology alone is insufficient and should not be used for adolescent diagnosis. Care must address endometrial protection, metabolic risk, psychological wellbeing and fertility goals rather than periods alone. Rapid virilisation requires urgent investigation for an androgen secreting ovarian or adrenal tumour.

PCOS is not diagnosed from ovarian appearance alone. Adults need two recognised features after other causes are excluded, while adolescents require both ovulatory dysfunction and hyperandrogenism. Management combines endometrial protection, metabolic prevention, symptom treatment, psychological support and fertility care shaped by personal goals.