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Primary and secondary amenorrhoea
In every amenorrhoea the first step is a pregnancy test; then TSH, prolactin and FSH sort the causes by their level in the axis — hypothalamus, pituitary, ovary or uterus.
Why it matters in the exam
Amenorrhoea questions are almost always built on an algorithm. In secondary amenorrhoea (no period for 3 months in a previously regular cycle, or 6 months in an irregular one) pregnancy is excluded, then TSH, prolactin and FSH are measured. A high FSH in a woman under 40 indicates premature ovarian insufficiency (POI). A low or normal FSH with a low oestradiol points to hypothalamic amenorrhoea — weight loss, heavy exercise and stress. A raised prolactin calls for a search for drugs and a pituitary MRI. After curettage, normal hormones and no bleeding suggest intrauterine adhesions (Asherman).
In primary amenorrhoea (no period by age 15 with breast development, or by age 13 without breast development) the two deciding questions are: are there breasts (that is, oestrogen), and is there a uterus. No breasts with a high FSH — gonadal dysgenesis (Turner, 45,X); no breasts with a low FSH — central hormone deficiency (Kallmann with an impaired sense of smell) or constitutional delay. Breasts without a uterus — MRKH (karyotype 46,XX, female testosterone, normal pubic hair) or androgen insensitivity (46,XY, testosterone in the male range, scant pubic hair). Cyclical pain with a bluish bulge at the vaginal opening points to an imperforate hymen.
Key points
- Secondary amenorrhoea: 3 months in a regular cycle or 6 months in an irregular one.
- Pregnancy first; then TSH, prolactin and FSH.
- High FSH under 40 → POI → karyotype and FMR1.
- Low FSH with low weight or sport → hypothalamic amenorrhoea.
- Primary amenorrhoea: breasts? uterus? → Turner, MRKH or androgen insensitivity.
Summary table
| Condition | Deciding finding | Test | Treatment or note |
|---|---|---|---|
| Premature ovarian insufficiency (POI) | High FSH on two tests, under age 40 | Karyotype and FMR1 (fragile X premutation) | Hormone therapy until about the age of natural menopause |
| Hypothalamic amenorrhoea | Low or normal FSH, low oestradiol; low weight, sport, stress | History, exclusion of other causes | Nutrition and correction of energy balance; protect the bone |
| Raised prolactin | Galactorrhoea, amenorrhoea | Check drugs and TSH; pituitary MRI | Cabergoline |
| Asherman | After curettage; normal hormones | Hysteroscopy | Hysteroscopic removal of adhesions |
| Turner (45,X) | Primary amenorrhoea, short stature, no breasts, high FSH | Karyotype | Oestrogen; cardiac and renal follow-up |
| MRKH versus androgen insensitivity | Breasts without a uterus | Karyotype and testosterone | MRKH: 46,XX; insensitivity: 46,XY — gonadectomy later |
A free exam question
At what age primary amenorrhea investigation should be started in a girl with breast buds and pubic hair?
- A. 13
- B. 15
- C. 17
- D. 8
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Sources
- ACOG Committee Opinion No. 349, 2006, reaffirmed — Menstruation in Girls and Adolescents: Using the Menstrual Cycle as a Vital Sign
- ESHRE Guideline, 2024 — Management of women with premature ovarian insufficiency
- Endocrine Society Clinical Practice Guideline, 2017 — Functional Hypothalamic Amenorrhea
- Speroff's Clinical Gynecologic Endocrinology and Infertility, 9th edition (2019) — Amenorrhea
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.