Hormonal Evaluation and Testing

HPO Axis & Key Players - Hormone Harmony HQ

The Hypothalamic-Pituitary-Ovarian (HPO) axis governs female reproduction through precise hormonal interplay and feedback.

• Hypothalamus: Releases GnRH (pulsatile).
• Anterior Pituitary: GnRH triggers FSH & LH release.
  • FSH: Follicular growth, Estrogen ($E_2$) synthesis.
  • LH: Ovulation, corpus luteum, Progesterone synthesis.
• Ovaries: Produce key hormones.
  • Estrogen ($E_2$): Proliferative effects, feedback.
  • Progesterone: Secretory effects, feedback.
  • Inhibin: Suppresses FSH.
• Feedback:
  • Negative: $E_2$/Progesterone/Inhibin on hypothalamus/pituitary.
  • Positive: High $E_2$ → LH surge.

⭐ The pulsatile nature of GnRH secretion is essential; continuous GnRH administration leads to downregulation of pituitary receptors and suppressed gonadotropin release.

Ovarian Reserve Testing - Egg Timer Check

• Assesses quantity & quality of remaining oocytes.
• Key Tests:
  • Anti-Müllerian Hormone (AMH):
    • Produced by granulosa cells of preantral & small antral follicles.
    • Stable throughout menstrual cycle.
    • Normal: 1.5 - 4.0 ng/mL. ↓ AMH indicates ↓ ovarian reserve.
  • Antral Follicle Count (AFC):
    • Transvaginal ultrasound (TVS) count of follicles 2-10 mm in both ovaries (early follicular phase).
    • Good reserve: AFC > 10-15; Poor reserve: AFC < 5-7.
  • Day 3 FSH & Estradiol (E2):
    • FSH: Normal < 10 mIU/mL. ↑ FSH suggests ↓ reserve.
    • E2: Normal < 50-80 pg/mL. ↑ E2 (with normal FSH) can mask poor reserve.

⭐ AMH is currently considered one of the most reliable markers of ovarian reserve and correlates well with oocyte yield during IVF procedures.

• Other tests: Clomiphene Citrate Challenge Test (CCCT), Inhibin B (less common).

Ovulation & Luteal Phase Testing - Cycle Sleuth

• Ovulation Detection Methods:
  • BBT: Biphasic; ↑ 0.5-1°F post-ovulation.
  • Urinary LH Kits: Detect LH surge 24-36h prior.
  • Serum Progesterone (Mid-luteal, e.g., Day 21):

    • 3 ng/mL = Ovulation occurred.

    • 10 ng/mL = Adequate luteal function.

  • Ultrasound (Folliculometry): Monitors follicle, confirms rupture.
• Luteal Phase Evaluation:
  • Serum Progesterone (as above).
  • Luteal Phase Length: <10-12 days suggests defect.
  • Endometrial Biopsy (rare): Dating lag >2 days.

⭐ > Mid-luteal serum progesterone (>3 ng/mL) is key to confirm ovulation retrospectively.

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Androgen, Prolactin & Thyroid Tests - Hormone Hotspots

• Androgens (Testosterone, DHEAS):
  • Indications: Hirsutism, virilization, irregular menses, PCOS suspicion.
  • Total Testosterone: If ↑, consider SHBG.
  • DHEAS: Adrenal androgen marker.
• Prolactin (PRL):
  • Indications: Galactorrhea, amenorrhea, infertility.
  • Rule out: Pregnancy, drug-induced, stress.
  • Macroprolactin if PRL mildly ↑.

  ⭐ Prolactinomas are the most common pituitary adenomas; PRL >100 ng/mL is highly suggestive.

• Thyroid (TSH, free T4):
  • Indications: Menstrual irregularities, infertility, goiter, hypo/hyperthyroid symptoms.
  • TSH: Best initial screening test for thyroid dysfunction impacting reproduction.
  • Subclinical hypothyroidism (↑TSH, normal fT4) can affect fertility. 📌 Thyroid Status Helps (TSH).

High‑Yield Points - ⚡ Biggest Takeaways

• Day 2/3 FSH, LH, Estradiol and AMH assess baseline ovarian reserve.
• AMH is a key cycle-independent marker of the ovarian follicular pool.
• Mid-luteal (Day 21) serum progesterone confirms ovulation.
• TSH and Prolactin are vital initial tests for amenorrhea and infertility.
• For hirsutism/virilization, evaluate serum testosterone and DHEAS.
• 17-hydroxyprogesterone (17-OHP) is crucial for diagnosing non-classical CAH.
• Always perform an hCG test to rule out pregnancy first.