Amenorrhea

🔍 When to Suspect

Individuals who have never started periods (primary amenorrhea) or whose regular periods have stopped for ≥3 cycles or >6 months (secondary amenorrhea)

From the full topic in The Ocean Library: Amenorrhoea

🧭 When to suspect

Suspect primary amenorrhoea in females who have not started menstruation by age 13 (if no secondary sexual characteristics are present) or by age 15 (if secondary characteristics are present).

Suspect secondary amenorrhoea if menstruation has stopped for ≥ 3 months (in previously regular cycles) or ≥ 6 months (in previously irregular cycles).

Patients may present with absent periods alongside symptoms such as galactorrhoea, hirsutism, acne, or significant weight changes. The most useful first step is to localise the problem to one of four levels – but in every case, pregnancy is the single most common cause of secondary amenorrhoea and must be excluded first.

Level	Representative causes
Hypothalamic	Functional hypothalamic amenorrhoea (low weight, excessive exercise, stress); Kallmann syndrome (with anosmia).
Pituitary	Hyperprolactinaemia / prolactinoma; other pituitary tumours; Sheehan syndrome.
Ovarian	PCOS (the commonest cause of oligo/amenorrhoea); premature ovarian insufficiency; Turner syndrome.
Outflow / structural	Imperforate hymen; Müllerian agenesis (MRKH); Asherman syndrome; androgen insensitivity syndrome.
Other endocrine	Thyroid disease; Cushing's syndrome – and, in all cases, pregnancy.

Source: NICE

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