Primary Amenorrhea

Definition & Initial Approach - No Flow Show

⭐ Primary amenorrhea is defined as no menses by age 15 with normal secondary sexual characteristics (SSC), OR by age 13 if no SSC are present.

• Initial Assessment Protocol:
  • Comprehensive History:
    • Perinatal, developmental milestones, growth velocity.
    • Nutritional status, exercise intensity, psychological stress.
    • Family history of pubertal delay/genetic conditions.
    • Symptoms of virilization or galactorrhea.
  • Detailed Physical Examination:
    • Anthropometry: Height, weight, BMI, arm span.
    • Tanner staging for breast & pubic hair development.
    • External genitalia: Vaginal patency, clitoral size, imperforate hymen.
    • Systemic: Stigmata of Turner's (e.g., webbed neck, shield chest), PCOS.
  • Crucial First Step: Exclude pregnancy (serum β-hCG).
  • Baseline Investigations:
    • Pelvic Ultrasound: Assess uterus, ovaries, adnexa.
    • Hormonal Profile: FSH, LH, Estradiol, TSH, Prolactin.

Etiology Unveiled - The Why Files

• I. Hypothalamic-Pituitary Causes (↓FSH/LH - Hypogonadotropic Hypogonadism)
  • Functional: Stress, excessive exercise, anorexia nervosa.
  • Kallmann Syndrome: GnRH deficiency, anosmia.
  • CNS lesions: Craniopharyngioma, pituitary adenoma.
  • Constitutional delay: Common, family history.
• II. Ovarian Causes (↑FSH/LH - Hypergonadotropic Hypogonadism)

  ⭐ Gonadal dysgenesis (e.g., Turner syndrome 45,XO with streak gonads) is the most common cause of primary amenorrhea, characterized by hypergonadotropic hypogonadism (↑FSH/LH).

  • Premature Ovarian Insufficiency (POI): Ovarian follicle depletion <40 years.
• III. Outflow Tract Defects (Normal FSH/LH - Eugonadotropic)
  • Müllerian Agenesis (MRKH): Absent uterus/upper vagina; normal ovaries, 46,XX.
  • Imperforate Hymen: Bulging, bluish membrane.
  • Androgen Insensitivity Syndrome (AIS): 46,XY; phenotypically female, absent uterus.

Diagnostic Pathway - Sleuth Central

⭐ A stepwise diagnostic approach for primary amenorrhea involves: 1. Pregnancy test, 2. Pelvic ultrasound (uterus presence/absence), 3. FSH levels, 4. Karyotyping (if indicated, e.g., high FSH or uterine anomaly).

• Initial: H&P (Tanner, virilization), rule out pregnancy.

Syndrome Spotlights - Case Files

• Turner Syndrome (45,XO): Short stature, webbed neck, ovarian dysgenesis (streak gonads), ↑FSH/LH.
• Mayer-Rokitansky-Küster-Hauser (MRKH):

  ⭐ Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome (müllerian agenesis) is the second most common cause of primary amenorrhea, presenting with 46,XX karyotype, normal female secondary sexual characteristics, normal ovarian function, but absent uterus and upper vagina.

• Androgen Insensitivity (AIS) (46,XY): Phenotypically female, testes present, absent uterus, blind vagina, ↑Testosterone.
• Kallmann Syndrome: ↓FSH/LH, anosmia. 📌 KALLMANN = KAN'T smell.
• Swyer Syndrome (46,XY): Pure gonadal dysgenesis (streak gonads), phenotypically female, normal Müllerian structures, ↑FSH/LH.

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High‑Yield Points - ⚡ Biggest Takeaways

• Primary amenorrhea: No menses by age 15 (with secondary sexual traits) or 13 (without).
• Mullerian agenesis (MRKH): 46,XX, absent uterus/upper vagina; normal ovaries & development.
• Androgen Insensitivity Syndrome (AIS): 46,XY, female phenotype, absent uterus, testes present, ↑testosterone.
• Turner Syndrome (45,X0): Streak ovaries, short stature, no secondary sexual characteristics.
• Kallmann Syndrome: Hypogonadotropic hypogonadism with anosmia (GnRH deficiency).
• Workup: β-hCG, FSH, prolactin, TSH, ultrasound; consider karyotype.