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Amenorrhoea

Primary vs secondary and a stepwise work-up.

Source: Standard UK teaching

Definitions

Primary	No periods by 15 with normal sexual development (or by 13 with none).
Secondary	No periods ≥3 months (regular cycles) or ≥6 months (irregular).

Work-up

Pregnancy test first.
FSH, LH, oestradiol, prolactin, TSH, testosterone.
Pelvic ultrasound.
Karyotype if primary with high FSH.
MRI pituitary if prolactin high.

Causes

Hypothalamic	Weight loss, exercise, stress, Kallmann — low FSH/LH.
Pituitary	Prolactinoma, Sheehan’s.
Ovarian	POI, Turner (high FSH); PCOS.
Outflow	Asherman’s, MRKH, imperforate hymen, septum.

A summary for trained clinicians. Always check the full guideline, the patient in front of you and your hospital's protocol. Spotted an error? Tell us.