OG25.1 | Amenorrhea — Summary & Reflection

KEY TAKEAWAYS

Amenorrhea is classified as primary (no menarche by 15 yr with, or 13 yr without, secondary sexual characteristics) or secondary (≥3 months with regular prior cycles; ≥6 months with irregular cycles). The core diagnostic framework is compartment-based:

• Outflow/Uterine: normal hormones; normogonadotrophic; causes include MRKH (46XX, absent uterus, normal ovaries), CAIS (46XY — distinguish by karyotype), and Asherman syndrome (post-D&C or TB endometritis; negative both progesterone and combined challenges)
• Ovarian: hypergonadotrophic hypogonadism (high FSH, high LH, low oestradiol); Turner syndrome (45X0, primary, streak ovaries, somatic features) and POI (FSH >25 IU/L ×2, before 40 yr, HRT mandatory)
• Pituitary: hypogonadotrophic; prolactinoma (elevated prolactin, amenorrhea-galactorrhoea, dopamine agonist treatment), Sheehan syndrome (postpartum infarction, lifelong replacement), hyperprolactinaemia from hypothyroidism (always check TSH first)
• Hypothalamic: hypogonadotrophic; FHA (weight loss, excess exercise, stress; treat the cause first)
• PCOS: normogonadotrophic, anovulatory, hyperandrogenic; manage with OCP or ovulation induction

Investigation sequence: β-hCG first → TSH + prolactin → FSH/LH + oestradiol → progesterone challenge → combined oestrogen-progesterone challenge → karyotype + pelvic USG + pituitary MRI as directed. Management is cause-specific; all hypo-oestrogenic states require HRT for bone and cardiovascular protection; any uterine oestrogen therapy requires cyclical progestogen for endometrial protection.

REFLECT

Reflect on the two contrasting cases from the opening hook — Priya (MRKH: normal hormones, absent uterus, 46XX) and Meena (Asherman: post-curettage, normal hormones, non-responsive endometrium). Both present with amenorrhea; both have entirely normal FSH, LH, and oestradiol. Without the progesterone challenge and the two-stage interpretation framework, their compartment-level difference would be invisible on blood tests alone. Think about a patient you might encounter in your clinical years who presents with 'no periods'. Which one question in the history would you ask first to narrow the compartment — and why? How would you explain to a 22-year-old with FHA that her amenorrhea requires lifestyle change rather than a pill to restart her cycle? Connecting clinical reasoning (compartment thinking) to patient communication is the hallmark of the clinician this module prepares you to become.