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Polycystic Ovarian Syndrome for USMLE Step 1

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Polycystic Ovarian Syndrome (PCOS) for the USMLE Step 1 Exam
  • Definition:
    • Polycystic ovarian syndrome (PCOS) is a common endocrine disorder in women of reproductive age, marked by hyperandrogenism, menstrual irregularities, and polycystic ovaries. It is one of the leading causes of infertility and metabolic disturbances in women.
  • Etiology and Pathophysiology:
    • The cause of PCOS is multifactorial, involving genetic and environmental influences that lead to hormonal imbalance, primarily excess androgens and insulin resistance.
    • Hyperandrogenism:
    • Excess androgen production in the ovaries and adrenal glands leads to symptoms such as hirsutism, acne, and alopecia.
    • Insulin Resistance:
    • A frequent finding in PCOS, insulin resistance contributes to hyperinsulinemia, which stimulates ovarian androgen production and disrupts follicle development.
    • Follicular Dysfunction:
    • Disrupted folliculogenesis leads to anovulation and the presence of multiple small ovarian cysts.
PCOS hormones
Clinical Manifestations
  • Menstrual Irregularities:
    • Commonly presents as oligomenorrhea (infrequent periods) or amenorrhea (absence of periods), secondary to chronic anovulation.
  • Hyperandrogenism:
    • Hirsutism: Coarse, male-pattern hair growth on the face, chest, and abdomen.
    • Acne and Seborrhea: Due to high androgen levels stimulating sebaceous glands.
    • Alopecia: Male-pattern hair thinning or baldness in severe cases.
  • Metabolic Disturbances:
    • Obesity, insulin resistance, and dyslipidemia (elevated LDL and triglycerides, reduced HDL) are common.
    • Increased risk of type 2 diabetes mellitus (T2DM) and cardiovascular disease.
  • Infertility:
    • A significant cause of infertility due to chronic anovulation; even in cases where ovulation occurs, suboptimal endometrial receptivity can impair fertility.
  • Acanthosis Nigricans:
    • Dark, velvety patches of skin, especially in the neck, axillae, and groin, associated with insulin resistance.
Diagnostic Criteria
  • The Rotterdam criteria are most commonly used for diagnosing PCOS and require two of the following three features, provided other causes are excluded:
    • Oligo- or Anovulation: Irregular or absent menstrual cycles.
    • Hyperandrogenism: Clinical signs (hirsutism, acne) or elevated serum androgens.
    • Polycystic Ovaries on Ultrasound: ≥12 follicles in each ovary (2–9 mm) or increased ovarian volume (>10 mL).
  • Differential Diagnoses to Exclude:
    • Hyperprolactinemia, hypothyroidism, and androgen-secreting tumors can mimic PCOS symptoms.
    • Congenital Adrenal Hyperplasia (CAH): Screened with 17-hydroxyprogesterone levels.
Laboratory Evaluation
  • Hormonal Testing:
    • Total and Free Testosterone: Elevated in most PCOS cases due to hyperandrogenism.
    • LH and FSH: LH may be elevated, creating an elevated LH/FSH ratio, though this is not required for diagnosis.
    • Estradiol: Usually normal or slightly elevated due to unopposed estrogen production from anovulation.
  • Metabolic Screening:
    • Oral Glucose Tolerance Test (OGTT): Checks for insulin resistance or diabetes.
    • Lipid Profile: Assesses for dyslipidemia, which is common in PCOS.
Management
Pharmacologic Treatments
  • Hormonal Contraceptives:
    • Combined Oral Contraceptives (COCs): First-line treatment for menstrual irregularities and hyperandrogenic symptoms, reducing androgen levels and protecting the endometrium.
    • Progestin-Only Therapy: For women who cannot use estrogen, progestin can be used to regulate cycles and prevent endometrial hyperplasia.
  • Anti-Androgens:
    • Spironolactone: Commonly used to treat hirsutism and acne by blocking androgen receptors and inhibiting 5α-reductase.
    • Finasteride: Reduces dihydrotestosterone (DHT) levels and is sometimes used as an adjunct to spironolactone.
  • Metformin:
    • Improves insulin sensitivity, reduces blood glucose, and may help restore ovulation. Often used with lifestyle modifications to manage metabolic aspects of PCOS.
  • Ovulation Induction:
    • Letrozole: An aromatase inhibitor and preferred first-line agent for ovulation induction in PCOS-related infertility.
    • Clomiphene Citrate: An estrogen receptor modulator used to induce ovulation.
Key Points
  • PCOS is an endocrine disorder in reproductive-aged women, characterized by hyperandrogenism, ovulatory dysfunction, and polycystic ovaries.
  • Clinical Features include menstrual irregularities, hyperandrogenic signs (hirsutism, acne), metabolic abnormalities (insulin resistance, dyslipidemia), and infertility.
  • Diagnosis follows the Rotterdam criteria, requiring two of three findings (oligo/anovulation, hyperandrogenism, and polycystic ovaries) after ruling out other causes.
  • Management includes lifestyle modification (diet and exercise), hormonal therapy (COCs for cycle regulation), anti-androgens (e.g., spironolactone for hirsutism), and ovulation induction (letrozole for infertility).
  • Complications: Increased risk of endometrial hyperplasia, type 2 diabetes, cardiovascular disease, and obstructive sleep apnea.

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