Overview.
PCOS is the most common endocrine disorder in reproductive-age women, affecting 8-13% globally. It is characterized by a combination of hyperandrogenism, ovulatory dysfunction, and polycystic ovarian morphology. Despite the name, cysts are not required for diagnosis. PCOS carries significant metabolic implications, including elevated risk for insulin resistance, type 2 diabetes, and cardiovascular disease.
PCOS results from dysregulation of the hypothalamic-pituitary-ovarian (HPO) axis. Elevated LH pulses drive ovarian androgen overproduction, while insulin resistance amplifies androgens and suppresses SHBG. The net result is elevated free androgens, impaired follicle development, anovulation, and the characteristic hormonal pattern. The 2023 International Evidence-Based Guideline updated the Rotterdam criteria to allow AMH as an ultrasound alternative for adults.
Prevalence: Affects 8-13% of reproductive-age women worldwide. Up to 70% of affected women remain undiagnosed. It is the most prevalent female endocrine disorder globally.
Medical name: Polycystic Ovary Syndrome
Symptoms.
Early warnings
- Irregular or absent periods beginning at puberty
- Acne persisting beyond teenage years, especially jawline and chin
- Unwanted facial or body hair (hirsutism)
- Thinning scalp hair
- Difficulty losing weight
- Skin darkening in neck or armpits (acanthosis nigricans)
Classic symptoms
- Oligomenorrhea (cycles >35 days) or amenorrhea
- Hirsutism (modified Ferriman-Gallwey score >4-6)
- Acne and seborrhea
- Female-pattern alopecia
- Acanthosis nigricans
- Infertility due to anovulation
- Mood disorders (anxiety, depression)
- Obesity in 40-60% of cases (20-30% are lean PCOS)
Progression
PCOS is a lifelong condition. Metabolic risks accumulate over time — up to 35% develop impaired glucose tolerance and up to 10% develop type 2 diabetes within a decade. Menstrual cycles may paradoxically become more regular near menopause, but metabolic risk persists.
Risk factors.
- Family history of PCOS (first-degree relative)
- Obesity or metabolic syndrome
- Insulin resistance or type 2 diabetes
- South Asian or Middle Eastern ancestry (higher prevalence)
- Premature adrenarche
- Exposure to endocrine disruptors (emerging evidence)
Lab interpretation.
Key biomarkers
- Total Testosterone — Elevated or in upper quartile of normal; >50-60 ng/dL commonly seen in PCOS (primary)
- SHBG — Low (suppressed by insulin); amplifies free testosterone bioavailability (primary)
- LH — Elevated relative to FSH; LH:FSH ratio classically >2:1 in lean PCOS (primary)
- FSH — Normal or low-normal; serves as denominator in LH:FSH ratio (primary)
- AMH — Typically 2-4x above age-specific median; can substitute for ultrasound in adults (2023 guideline) (primary)
- Fasting Insulin / HOMA-IR — Elevated in 65-80%; HOMA-IR >2.5 indicates clinically significant insulin resistance (secondary)
- DHEA-S — Mildly elevated in adrenal PCOS phenotype; >700 mcg/dL warrants adrenal tumor workup (secondary)
- 17-OH Progesterone — Normal in PCOS; used to exclude congenital adrenal hyperplasia (CAH) (exclusion)
Diagnostic criteria
- Rotterdam criteria (2 of 3 required): oligo/anovulation, clinical or biochemical hyperandrogenism, polycystic ovarian morphology or elevated AMH
- Exclusions required: rule out thyroid dysfunction, hyperprolactinemia, non-classic CAH, Cushing's
- Adolescents: both hyperandrogenism AND ovulatory dysfunction required; ultrasound/AMH not needed
- Adults: AMH may substitute for ultrasound if both hyperandrogenism and anovulation are present, no further testing needed
Recommended panels
When & next steps.
When to test
- Irregular or absent periods, especially starting in adolescence
- Signs of androgen excess: hirsutism, acne, alopecia
- Difficulty conceiving
- Insulin resistance signs: acanthosis nigricans, obesity, weight gain
- Family history of PCOS or type 2 diabetes
- Abnormal cholesterol or elevated fasting glucose in reproductive-age woman
If suspected
- Order: total testosterone, SHBG, LH, FSH, AMH, prolactin, TSH, fasting glucose and insulin, HbA1c, lipid panel
- Consider pelvic ultrasound (transvaginal preferred in adults, if AMH inconclusive)
- Document menstrual cycle history (length, regularity, last period)
- Calculate BMI and assess for hirsutism (mFG score), acne, alopecia
- Rule out pregnancy before interpretation
If confirmed
- Lifestyle modification first: even 5-10% weight loss improves ovulatory function in overweight PCOS
- Combined oral contraceptive pill (COCP): first-line for menstrual regulation and androgen suppression
- Metformin: first-line for metabolic/insulin resistance management
- Letrozole: first-line ovulation induction for fertility (preferred per 2023 guideline)
- Annual glucose monitoring (HbA1c or fasting glucose) given diabetes risk
- Regular blood pressure, lipid, and weight monitoring
FAQs.
Do I need to have cysts to have PCOS?
No. The name is misleading — the follicles visible on ultrasound in PCOS are immature follicles, not true cysts. Polycystic ovarian morphology is just one of three Rotterdam criteria, and you only need two of three for diagnosis. Many women with PCOS have normal-appearing ovaries.
Can lean women have PCOS?
Yes. Approximately 20-30% of women with PCOS are lean (BMI <25). Lean PCOS tends to show a more pronounced LH:FSH imbalance, while obese PCOS shows more insulin resistance. Both phenotypes exist and require tailored management.
Does PCOS affect fertility permanently?
PCOS causes anovulatory infertility, but with appropriate ovulation induction (letrozole, clomiphene, gonadotropins, or IVF), the majority of women achieve pregnancy. Success rates are generally good, particularly in younger women.
Can PCOS resolve on its own?
The underlying hormonal dysregulation is typically lifelong, but symptoms can improve with weight management and treatment. Cycles may become more regular near menopause, but metabolic risk persists and requires ongoing monitoring.