ENDOCRINE CLINIC · ROTTERDAM REVIEW · TOPIC: PCOS · REF: ESHRE / Endocrine Society / ACOG

The Rotterdam Review Endocrine reference · U.S. edition

Endocrinology · Reproductive-metabolic

PCOS is not about ovarian cysts. It is an endocrine syndrome with three possible doors.

Roughly 1 in 10 women of reproductive age has polycystic ovary syndrome — and roughly 70 percent of them do not know it. It affects the menstrual cycle, skin, metabolism, and fertility, and it is diagnosed by meeting two of three criteria, not by any single test. This is the practical, evidence-based review.

15 min read

ESHRE-aligned

4 phenotypes · 4 drug classes

1 in 10

Women of reproductive age have PCOS — roughly 5 to 6 million in the United States.

~70%

Remain undiagnosed — many visit multiple clinicians before receiving an answer.

Phenotypes (A–D) — from full syndrome to mild ovulatory-only presentation.

3×

Increased risk of type 2 diabetes — screening is recommended even in lean patients.

Section 01 · The criteria

How PCOS is diagnosed — two of three, after excluding mimics.

The Rotterdam criteria, refined by ESHRE and endorsed by the Endocrine Society, define PCOS by the presence of at least two of three findings — once other conditions have been ruled out.

Criterion 1

Hyperandrogenism

Clinical: hirsutism (Ferriman-Gallwey score ≥ 8), persistent acne, or male-pattern hair loss. Biochemical: elevated total or free testosterone, or elevated DHEAS. Testosterone above 200 ng/dL warrants imaging for an androgen-secreting tumor.

Criterion 2

Ovulatory dysfunction

Cycles shorter than 21 days or longer than 35 days, or fewer than 8 cycles per year. Anovulation is the most common cause of infertility in PCOS. Cycle length alone is a reasonable surrogate when the pattern is clear.

Criterion 3

Polycystic ovaries on ultrasound

Twelve or more follicles (2–9 mm) in either ovary, or ovarian volume greater than 10 mL. These are immature follicles, not true cysts — the name is a misnomer. Not required for diagnosis.

Several conditions mimic PCOS and must be ruled out before diagnosis. Hypothyroidism can cause irregular periods and modest androgen elevation. Hyperprolactinemia suppresses ovulation. Non-classic congenital adrenal hyperplasia (21-hydroxylase deficiency) produces hyperandrogenism — the 17-hydroxyprogesterone level distinguishes it. Cushing's syndrome produces central obesity, hirsutism, and metabolic features. Androgen-secreting tumors of the ovary or adrenal gland present with rapid onset and markedly elevated androgens. Each of these changes the treatment entirely.

Section 02 · The hormonal cascade

Four nodes — and how they reinforce each other.

PCOS is not a single hormonal problem. It is a self-reinforcing loop involving the brain, the ovary, the adrenal gland, and the metabolic system.

The PCOS loop — four nodes

Each node amplifies the others

Raised GnRH pulse

Hypothalamic signaling favors LH over FSH. LH:FSH ratio often exceeds 2:1 — a classic but not universal finding.

→

Theca cells overproduce androgens

LH drives theca cell androgen synthesis. Testosterone and androstenedione rise, producing hirsutism and acne.

→

Follicles stall; ovulation fails

Androgens disrupt follicular maturation. Multiple small follicles accumulate and no dominant follicle emerges — anovulation follows.

→

Insulin resistance amplifies everything

High insulin stimulates ovarian androgen production and lowers SHBG — raising free testosterone — and drives metabolic risk.

Insulin resistance is present in most women with PCOS — including many at normal BMI. It is not a consequence of PCOS; it is part of the mechanism. This is why treatments that improve insulin sensitivity (weight loss, metformin, inositol) can restore ovulation and reduce androgens even in the absence of any weight change. It also explains why PCOS raises long-term risk of type 2 diabetes and metabolic syndrome independently of body weight.

Section 03 · Four phenotypes

Not all PCOS looks the same — and the phenotype matters.

Combining the three Rotterdam criteria produces four distinct phenotypes. Metabolic and cardiovascular risk is highest in phenotypes with hyperandrogenism, but every phenotype warrants monitoring.

Phenotype	Hyperandrogenism	Ovulatory dysfunction	Polycystic ovaries	Notes
A · Classic	✓	✓	✓	All three criteria. Highest metabolic and cardiovascular risk. Most common in clinical practice.
B	✓	✓	—	Hyperandrogenism and anovulation without ultrasound findings. Metabolic risk similar to A.
C	✓	—	✓	Ovulatory PCOS. Regular cycles but hyperandrogenism and polycystic appearance. Risk is intermediate.
D	—	✓	✓	Mildest phenotype. Metabolic risk lower but not zero. Diagnosis is debated by some societies.

Why phenotypes matter: insulin resistance and metabolic risk track most closely with hyperandrogenism. Phenotype A — full classic PCOS — carries the highest risk of type 2 diabetes, dyslipidemia, and metabolic syndrome. Phenotype D has the lowest, but even here, long-term follow-up studies show increased cardiometabolic risk compared to controls. Every phenotype warrants the same screening cadence, even if the intensity of treatment differs.

Section 04 · Symptoms by domain

Four domains — and what each one tells you.

PCOS symptoms cluster into four clinical domains. Which domains are involved — and how severe — determines the treatment priorities.

Menstrual & reproductive

Irregular cycles — intervals over 35 days or fewer than 8 per year
Amenorrhea — no period for 3 months or more
Heavy or prolonged bleeding when cycles do occur
Infertility — anovulation is the usual cause
Higher miscarriage risk, particularly with insulin resistance

Dermatologic & androgen

Hirsutism — coarse, dark hair on face, chest, back, abdomen
Acne — persistent, inflammatory, often along jaw and chin
Male-pattern hair loss — thinning at crown and temples
Skin tags and acanthosis nigricans — markers of insulin resistance

Metabolic

Insulin resistance — often present at normal BMI
Central adiposity — weight carried around the abdomen
Dyslipidemia — high LDL, low HDL, high triglycerides
Fatty liver — non-alcoholic steatosis is common
Elevated risk of type 2 diabetes — 3× the general population

Psychosocial & sleep

Anxiety — prevalence higher than in the general population
Depression — often underrecognized in PCOS care
Eating disorders — increased risk of binge eating
Sleep apnea — even in lean patients with PCOS
Reduced quality of life — often underaddressed in treatment

Section 05 · Treatment

Four drug classes — chosen based on what the patient wants.

PCOS treatment depends on the primary goal: regulating cycles, reducing androgens, restoring fertility, or improving metabolic health. These are not mutually exclusive, and often more than one is used.

Combined hormonal contraceptives

First-line for cycle control and androgens

Combined oral contraceptives (COCs) are first-line for cycle regulation and androgen reduction in patients who are not trying to conceive. Estrogen raises SHBG (which binds testosterone) and suppresses LH, reducing ovarian androgen production.

Low-androgenic progestins (norgestimate, desogestrel, drospirenone) are generally preferred. COCs do not treat the underlying metabolic dysfunction and do not improve insulin resistance. For patients with contraindications to estrogen (migraine with aura, smoking over 35, prior clot), progestin-only methods or a hormonal IUD are options — though these do not lower androgens.

Examplesnorgestimate-EE · drospirenone-EE · desogestrel-EE · Yaz · Ortho Tri-Cyclen

Metformin — insulin sensitizer

Adjunct · metabolic

Improves insulin sensitivity and, in some patients, restores ovulation and lowers androgens. Most useful in patients with documented insulin resistance or impaired glucose tolerance. Typical dose is 1,500–2,000 mg per day, extended-release to minimize GI effects.

Does not produce weight loss on its own but may modestly reduce weight gain. Often combined with lifestyle modification. Effect on hirsutism is modest — COCs remain more effective for androgen symptoms.

Examplesmetformin IR · metformin ER · (inositol — supplement, moderate evidence)

Spironolactone — anti-androgen for hirsutism

Off-label · 6+ months to see effect

Blocks the androgen receptor and reduces testosterone synthesis. Used off-label for hirsutism and acne in PCOS, typically at 50–100 mg twice daily. Takes 6 to 12 months to see meaningful hair reduction.

Must be used with reliable contraception — it is teratogenic. Contraindicated in pregnancy. Monitor potassium and kidney function. Often added when COCs alone do not adequately control hirsutism. Other options: finasteride (also teratogenic), eflornithine cream (facial hair only).

Examplesspironolactone · finasteride (off-label) · eflornithine topical

Letrozole — first-line ovulation induction

For fertility · 5-day course

Aromatase inhibitor. Now first-line for ovulation induction in PCOS — superior to clomiphene for both ovulation and live birth rates in randomized trials. Given as a 5-day course early in the cycle (typically 2.5–7.5 mg daily).

Clomiphene citrate remains an alternative but has higher rates of multiple pregnancy and anti-estrogenic side effects. For patients who fail oral agents, options include gonadotropins, ovarian drilling, and IVF. Metformin combined with letrozole improves outcomes in insulin-resistant patients.

Examplesletrozole · clomiphene citrate · gonadotropins · metformin adjunct

Lifestyle modification remains foundational. In patients carrying excess weight, a 5 to 10 percent weight loss can restore ovulation, improve insulin sensitivity, lower androgens, and improve response to fertility treatments. Diet quality — particularly reducing refined carbohydrates and added sugars — affects metabolic markers even without weight loss. Regular physical activity improves insulin sensitivity independently of weight change.

For psychological support: PCOS is associated with increased rates of anxiety, depression, and eating disorders. Screening for these should be routine, not optional, and treatment should include mental health support when indicated.

Section 06 · Long-term screening

What to monitor — and how often.

PCOS is a lifelong condition with metabolic and reproductive consequences. Regular screening is the intervention that catches complications early.

Recommended screening cadence

Individualize based on phenotype and risk factors

Every 1–3 years

Oral glucose tolerance test or A1C

Type 2 diabetes screening is the single most important long-term check. Begin at diagnosis regardless of BMI, then repeat based on risk factors. Fasting glucose alone may miss early impairment.

Every 1–3 years

Lipid panel

Dyslipidemia is common in PCOS. Low HDL and elevated triglycerides are typical. Screen at diagnosis and periodically thereafter, especially with obesity or family history of early cardiovascular disease.

Annually or as indicated

Blood pressure

Hypertension is more prevalent in PCOS, particularly with metabolic syndrome. Blood pressure should be checked at every routine visit.

If amenorrhea > 3 months

Endometrial protection

Chronic unopposed estrogen from anovulation increases endometrial hyperplasia and cancer risk. Cycles should be induced at least every 3 months with COCs, cyclic progestin, or a hormonal IUD if pregnancy is not desired.

Every 1–2 years

Depression and anxiety screening

PHQ-9 and GAD-7 are quick, validated tools. Mood disorders are significantly more common in PCOS and often underrecognized when care focuses only on hormones.

When indicated

Sleep apnea screening

Especially with obesity, snoring, or excessive daytime sleepiness. Sleep apnea is more common in PCOS and often underdiagnosed. Treating it can improve insulin sensitivity.

Section 07 · What to watch for

Features that suggest something other than PCOS.

Rule out other causes

If any of these appear, the diagnosis needs to be reconsidered or extended.

Rapid onset of hirsutism or virilization — deepening voice, clitoromegaly, muscle bulk. Suggests an androgen-secreting tumor of the ovary or adrenal gland. Requires urgent imaging.

Total testosterone above 200 ng/dL or DHEAS markedly elevated. Not typical of PCOS and warrants tumor evaluation.

Cushingoid features — central obesity with moon face, purple striae, easy bruising, proximal muscle weakness. Screen for Cushing's syndrome with late-night salivary cortisol or 24-hour urine cortisol.

Severe or refractory hypertension with hypokalemia. Suggests primary aldosteronism or another secondary cause, which is more common in PCOS and important to detect.

Galactorrhea or amenorrhea with a normal LH/FSH ratio. Check prolactin — hyperprolactinemia suppresses ovulation and mimics PCOS.

Family history of very early cardiovascular disease or severe dyslipidemia. Consider familial hypercholesterolemia and additional risk stratification beyond routine PCOS care.

Section 08 · Access & affordability

PCOS medication is mostly generic. The price still varies.

Most PCOS medications are available as low-cost generics in the United States. Combined oral contraceptives, metformin, spironolactone, letrozole, and clomiphene are all generic and priced well below their original brand versions. Under the Affordable Care Act, most private insurance plans must cover contraception without cost-sharing, which includes COCs prescribed for PCOS. Metformin is often on $4 generic lists. Letrozole and clomiphene are inexpensive and frequently covered for fertility indications.

What still varies at the pharmacy counter: the same generic tablet can cost several times more at one licensed pharmacy than another. For chronic medications like metformin or COCs taken for years, even modest differences per fill add up. A live prescription price comparison shows the current range in about two minutes, and the same logic applies to every generic on a patient's list. If you are filling an online refill for the first time, the process is documented step by step in this how to order prescriptions online guide — prescription first, licensed seller second, small first order third.

Two practical notes specific to PCOS: do not stop metformin or COCs because a symptom improves — the underlying endocrine dysfunction persists, and stopping abruptly usually brings symptoms back within weeks to months. And do not skip doses to stretch a prescription, particularly for COCs — irregular use in PCOS can trigger breakthrough bleeding and further cycle disruption.

Before filling from any seller — online or local — verify them. A working VIPPS seal that resolves to a live NABP record, a real U.S. street address, and a prescription requirement that cannot be waived. A transparency page like this one about Metformin4You is a reasonable example of the standard to expect.

Section 09 · Questions

Five asked most often at the endocrine clinic.

Q·01 How is PCOS diagnosed? +

PCOS is diagnosed using the Rotterdam criteria, which require at least two of three findings after excluding other causes: clinical or biochemical hyperandrogenism, ovulatory dysfunction (irregular or absent periods), and polycystic ovaries on ultrasound. Diagnosis is clinical, not based on any single test.

Q·02 Do you have to have ovarian cysts to have PCOS? +

No. Despite the name, ovarian cysts are not required for the diagnosis. PCOS refers to immature follicles visible on ultrasound, not true cysts — and someone with two of the other criteria (hyperandrogenism and irregular periods) can have PCOS with entirely normal-appearing ovaries.

Q·03 Is PCOS caused by weight? +

PCOS is not caused by weight, but weight and PCOS influence each other. Many people with PCOS have insulin resistance independent of body weight, and PCOS occurs in people at every BMI. That said, weight loss of 5 to 10 percent can meaningfully improve insulin sensitivity, restore ovulation, and reduce androgen levels in people who carry excess weight.

Q·04 Does PCOS mean I cannot get pregnant? +

No. PCOS is one of the most common and most treatable causes of infertility. Many people with PCOS conceive naturally, and for those who need help, ovulation induction with letrozole is highly effective — often more effective than clomiphene in PCOS. IVF remains an option for those who do not respond to oral agents.

Q·05 What are the long-term risks of PCOS? +

PCOS is associated with increased risk of type 2 diabetes, gestational diabetes, metabolic syndrome, non-alcoholic fatty liver disease, endometrial hyperplasia and endometrial cancer (from chronic unopposed estrogen), and cardiovascular risk factors. Regular metabolic screening — at least every 1 to 3 years — is recommended even in lean patients.

◆ Sources & Verification

This reference is aligned with public clinical guidance from the European Society of Human Reproduction and Embryology (ESHRE) International PCOS Guideline, the Endocrine Society Clinical Practice Guidelines, the American College of Obstetricians and Gynecologists (ACOG), and the U.S. Food and Drug Administration's BeSafeRx program. Drug-label information draws on the National Library of Medicine's DailyMed database and MedlinePlus. Pharmacy verification follows the NABP VIPPS program.

◆ Before the next refill

PCOS is manageable. The medication should be affordable.

COCs, metformin, spironolactone, and letrozole are all available as low-cost generics, and the same tablet can cost several times more at one licensed pharmacy than another. A two-minute comparison across licensed U.S. sellers is a useful habit to build. Begin with the current Metformin price comparison as a live demonstration of how wide the spread runs.

Open the price comparison