What initial investigations should I consider for a patient presenting with primary amenorrhoea?

For a patient presenting with primary amenorrhoea, the initial consideration in primary care is to refer them to secondary care for specialist investigation and management of the underlying cause ¹.

Referral to secondary care should be considered for:

• Girls who have no secondary sexual characteristics and have not started menstruating by 13 years of age ¹.
• Girls with normal secondary sexual characteristics who have not started menstruating by 15 years of age ¹.
• Girls who have not started menstruating 3 years after thelarche (onset of breast development) or 5 years after thelarche if that occurred before the age of 10 ¹.

Earlier referral should be considered if an abnormality is suspected, such as in those with:

• Abdominal or pelvic pain ¹.
• Growth retardation ¹.
• Symptoms and signs of androgen excess (such as hirsutism) or thyroid disease ¹.
• Galactorrhoea ¹.
• Suspected genital tract malformation, intracranial tumour (for example, prolactinoma), or chromosomal anomaly (for example, Turner's syndrome or androgen insensitivity) ¹.
• Suspected eating disorder, which requires immediate referral to a community-based, age-appropriate eating disorder service ¹.

Referral to a gynaecologist, preferably with a special interest in adolescent gynaecology, is appropriate for most girls with primary amenorrhoea ¹. Referral to an endocrinologist is recommended for girls not showing any secondary sexual characteristics by age 13, or those with hyperprolactinaemia, thyroid disease, or features of androgen excess ¹. Explicit UK-based recommendations on primary care management and when to refer are lacking in published literature, with recommendations based on expert opinion due to the specialist nature of required investigations ¹.