🔑 Key Learning

  • Amenorrhoea is classified into primary (failure to menstruate by age 13–15) and secondary (cessation of periods for ≥3–6 months).
  • Causes range from physiological (pregnancy, menopause) to endocrine (prolactinoma, PCOS, hypothyroidism) and structural (Turner’s).
  • PCOS presents with oligo/amenorrhoea, hyperandrogenism, and polycystic ovaries on scan.
  • Turner’s syndrome is a classic cause of primary amenorrhoea with absent secondary sexual characteristics.
  • Investigations are guided by age, secondary sexual development, and hormonal profile (FSH/LH/testosterone/prolactin).

📆 The Menstrual Cycle

Phase 1: Menstruation (Day 1–4)

  • Shedding of endometrial lining due to falling oestrogen and progesterone.

Phase 2: Proliferative (Follicular) Phase (Day 5–13)

Ovarian changes:

  • FSH stimulates growth of ovarian follicles.
  • One becomes dominant and secretes increasing oestradiol.

Endometrial changes:

  • Endometrial proliferation begins.

Hormonal:

  • Rising oestradiol (from dominant follicle) leads to LH surge → triggers ovulation.

Cervical mucus:

  • Becomes clear and stretchy just before ovulation.

Temperature:

  • Slight drop in basal body temp just before ovulation.

Phase 3: Ovulation (Day 14)

  • LH surge causes release of oocyte.

Phase 4: Secretory (Luteal) Phase (Day 15–28)

Ovarian changes:

    • An ovarian follicle forms into the corpus luteum after the release of the oocyte during ovulation
    • The corpus luteum secretes progesterone.

Endometrial changes:

  • Endometrium becomes secretory and receptive to implantation.

If no fertilisation occurs:

  • Corpus luteum degenerates → progesterone and oestradiol fall → menstruation.
The menstural cycle. Isometrik, Kaldari; Begoon; Marnanel, CC BY-SA 3.0, via Wikimedia Commons

     

đźš« Amenorrhoea: Background

  • Primary amenorrhoea: No menstruation by:
    • 15 years with secondary sexual characteristics
    • 13 years if no secondary sexual characteristics
  • Secondary amenorrhoea: The cessation of menstruation in a woman with previous menses for:
    • ≥3 months (previously regular cycles)
    • ≥6 months if history of oligomenorrhoea

🧬 Causes of Primary Amenorrhoea

With normal secondary sexual characteristics:

  • Constitutional delay (family history)
  • Endocrine: Thyroid dysfunction, hyperprolactinaemia, Cushing’s
  • Androgen insensitivity syndrome

With absent secondary sexual characteristics:

  • Turner’s syndrome (45XO)
  • Primary ovarian insufficiency
  • Hypothalamic dysfunction: stress, weight loss, excessive exercise

🧬 Causes of Secondary Amenorrhoea

With hyperandrogenism:

  • PCOS
  • Cushing’s syndrome

Without hyperandrogenism:

  • Pregnancy/lactation
  • Menopause
  • Premature ovarian insufficiency
  • Hypothalamic dysfunction
  • Pituitary: Prolactinoma
  • Thyroid dysfunction

🔬 Investigations for Amenorrhoea

Primary Amenorrhoea

Referral to a specialist is recommended. Investigations may include:

  • Pelvic US – check uterus/ovaries
  • FSH/LH – elevated in ovarian failure - Turner's syndrome
  • Prolactin – >1000 → prolactinoma
  • TFTs
  • Testosterone – raised in androgen insensitivity (can be modestly raised in PCOS)
  • Karyotype – e.g. 45XO for Turner’s

Secondary Amenorrhoea

  • FSH/LH – high in premature ovarian insufficiency, low in hypothalamic causes
  • Prolactin
  • TFTs
  • Testosterone – for PCOS/hyperandrogenism
  • Pelvic USS – >12 follicles or >10cmÂł ovarian volume suggests PCOS

🎯 Turner Syndrome

Pathophysiology

  • Genetics: 45X,O
  • 1 in 2500 females

Clinical Features

  • Short stature, webbed neck, wide carrying angle
  • Shield chest with wide-spaced nipples
  • Primary amenorrhoea (streak ovaries)
  • Hypothyroidism common - affects 1/3rd patients (Hashimoto's)
Figure 262: Turner Syndrome. Note the neck webbing.

Associated Conditions

  • Coarctation of the aorta, VSD
  • Horseshoe kidney
  • Infertility

Diagnosis and Management

  • Karyotyping
  • Growth hormone, oestrogen replacement

🌰 Polycystic Ovarian Syndrome (PCOS)

Pathophysiology

  • Insulin resistance, hyperinsulinaemia
  • Elevated LH and androgens

Clinical Features

  • Oligo/amenorrhoea
  • Hirsutism, acne
  • Acanthosis nigricans, obesity
  • Subfertility

Investigations

  • Raised LH:FSH ratio
  • Mildly raised testosterone
  • Low SHBG
  • Pelvic USS: ≥12 follicles or ovarian volume >10cmÂł

Diagnosis: Rotterdam Criteria (2 of 3)

  1. Oligo/amenorrhoea
  2. Hyperandrogenism (clinical or biochemical)
  3. Polycystic ovaries on USS

Management

  • COCP for acne/hirsutism
  • Weight loss
  • Clomifene for fertility
  • Metformin may be used

đź“ť Exam Clues & Clinchers

  • Short girl with webbed neck, amenorrhoea, widely spaced nipples → Turner’s syndrome (45XO)
  • Oligomenorrhoea + acne + hirsutism + obesity → PCOS
  • Amenorrhoea + low FSH/LH + recent stress/weight loss → Hypothalamic dysfunction
  • Amenorrhoea + high prolactin → Prolactinoma
  • Amenorrhoea + high FSH in woman <40 → Premature ovarian failure
  • Primary amenorrhoea + normal breast development + absent uterus → Androgen insensitivity syndrome

đź”— Useful Links & References