Hormonal Evaluation and Testing

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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.

Basal Body Temperature (BBT) Chart for Ovulation Trackingoka

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.
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Practice Questions: Hormonal Evaluation and Testing

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A middle-aged female presents with increasing visual loss, breast enlargement, and irregular menses. What is the most appropriate investigation to diagnose the underlying condition?

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Flashcards: Hormonal Evaluation and Testing

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In polycystic ovarian syndrome, excess androgen (from theca cells) is converted to _____ in adipose tissue, which inhibits FSH secretion from anterior pituitary

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In polycystic ovarian syndrome, excess androgen (from theca cells) is converted to _____ in adipose tissue, which inhibits FSH secretion from anterior pituitary

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Hormonal Evaluation and Testing - Free Indian Medical PG