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Paediatric gynaecology

Primary amenorrhoea, why periods have not started and what to do about it.

Missing periods in a teenager is a signal, not a verdict. A structured paediatric assessment finds the cause and shapes a plan that protects puberty, bones and future fertility.

A radiographer guides a patient onto the bed of an advanced 3 Tesla MRI scanner in a London imaging suite

Why trust this guide

  • 01

    Editorial team

    Written by our editorial team from the UK sources listed on each page.

  • 02

    Sourced from guidance

    Checked against NICE, RCOG, BSPED and peer-reviewed paediatric endocrine sources you can see at the end.

  • 03

    Current for 2026

    Reflects modern UK guidance on primary amenorrhoea, RED-S, hypogonadism and MDT paediatric gynaecology care.

Key facts

Primary amenorrhoea at a glance.

The essentials, in plain English. What it means, why it matters and how UK paediatric teams work it up.

  • What it is

    Primary amenorrhoea is no menses by age 15 with normal secondary sexual characteristics, no menses by 13 without them, or no menses more than 3 years after thelarche.

  • Why it matters

    It can signal hypothalamic, pituitary, ovarian, chromosomal or anatomical problems that need timely paediatric endocrine and gynaecology input.

  • Common causes

    Functional hypothalamic amenorrhoea, PCOS, Turner syndrome, imperforate hymen and Mullerian agenesis top the list in UK adolescents.

  • Key hormone pattern

    Low LH and FSH point to hypothalamic or pituitary causes; high LH and FSH point to primary ovarian failure such as Turner or Swyer syndrome.

  • First-line tests

    Pregnancy test, TSH, prolactin, FSH, LH, oestradiol, androgens, plus pelvic ultrasound and karyotype when indicated.

  • Bone health

    Amenorrhoea lasting more than 6 months warrants DEXA, with calcium, vitamin D and weight-bearing exercise built into the plan.

Why this guide matters

Four categories of cause, one calm plan.

Primary amenorrhoea splits into hypogonadotropic, hypergonadotropic, eugonadotropic and anatomical causes. The category shapes the tests and the treatment.

  • Hypogonadotropic

    Low LH and FSH with low oestradiol. Functional hypothalamic amenorrhoea, RED-S, Kallmann syndrome, pituitary tumour, hyperprolactinaemia, thyroid disease and chronic illness sit here.

  • Hypergonadotropic

    High LH and FSH with low oestradiol. Turner syndrome (45,X), Swyer syndrome (46,XY DSD), premature ovarian insufficiency and chemo or radiotherapy damage are the classic causes.

  • Eugonadotropic

    Normal gonadotrophins. PCOS, thyroid dysfunction, hyperprolactinaemia and obesity-related anovulation belong in this group.

  • Anatomical / outflow

    Imperforate hymen, transverse vaginal septum, Mullerian agenesis (MRKH) and androgen insensitivity syndrome (AIS, 46,XY) all obstruct or absent the outflow tract.

How the diagnosis is made

From a first review to a clear MDT plan.

The steps a UK paediatric team will normally follow, in order. Growth, hormones, imaging and karyotype build the picture.

  1. 01

    Assessing

    Growth chart and Tanner staging

    Plot height and weight trajectory, assess Tanner stages and compare with mid-parental height to see where puberty has stalled.

  2. 02

    Assessing

    Full paediatric history

    Nutrition, exercise volume, eating behaviours, stress, chronic illness, medications, family menarche age and neonatal or surgical history.

  3. 03

    Assessing

    Pregnancy test and baseline bloods

    Pregnancy test in every adolescent, then TSH, prolactin, FSH, LH and oestradiol to place the axis.

  4. 04

    Confirming

    Androgens and metabolic screen

    Total testosterone, SHBG, free androgen index, 17-hydroxyprogesterone and HbA1c when hirsutism, acne or PCOS features are present.

  5. 05

    Confirming

    Pelvic ultrasound or MRI

    Confirms uterus and ovarian anatomy, streak ovaries, imperforate hymen, transverse vaginal septum or Mullerian agenesis.

  6. 06

    Confirming

    Karyotype when indicated

    Sent for hypergonadotropic hypogonadism, short stature or primary amenorrhoea with absent uterus to identify Turner, Swyer or AIS.

  7. 07

    Planning

    DEXA and MDT plan

    DEXA if amenorrhoea exceeds 6 months and referral to a paediatric endocrinology, gynaecology and psychology MDT for a joined-up plan.

Typical timeline: a first paediatric review to a settled MDT plan across a few weeks.

Symptoms

What primary amenorrhoea looks like.

The features that bring an adolescent to a paediatric gynaecology or endocrine clinic, plus the pattern that means it is time to escalate.

  • No menses by age 15

    No period by 15 despite normal breast development is the classic threshold for primary amenorrhoea.

  • No puberty by age 13

    No breast budding or pubic hair by 13 suggests delayed puberty and warrants full endocrine review.

  • Cyclical pelvic pain, no bleeding

    Monthly pain without periods raises the flag for imperforate hymen or a transverse vaginal septum trapping menstrual blood.

  • Short stature and webbed neck

    Turner syndrome features include short stature, webbed neck, wide-spaced nipples and cardiac or renal anomalies.

  • Low weight, high training load

    Underweight teens, dancers, gymnasts and endurance athletes commonly present with functional hypothalamic amenorrhoea and RED-S.

  • Hirsutism, acne, weight gain

    Androgen excess with irregular or absent periods points towards PCOS or a rarer virilising cause.

  • Anosmia with delayed puberty

    A reduced sense of smell alongside absent puberty suggests Kallmann syndrome, a form of congenital GnRH deficiency.

  • Red flag - bulging blue hymen

    A tense, bluish bulge at the introitus with cyclical pain is an imperforate hymen and needs urgent gynaecology review.

Treatment

How primary amenorrhoea is treated in the UK.

Treat the underlying cause, restore the hormonal environment, correct the anatomy where needed, and wrap the plan with psychology and bone protection.

  • Nutritional restoration

    For functional hypothalamic amenorrhoea and RED-S, restoring energy availability and moderating training is the foundation of care.

  • Hormone replacement therapy

    Transdermal oestradiol with cyclical progesterone is used in Turner syndrome and other hypogonadism to induce puberty and protect bone.

  • Combined hormonal therapy

    A combined pill or cyclical progestogen can regulate cycles in PCOS and eugonadotropic amenorrhoea once diagnosis is clear.

  • Dopamine agonist

    Cabergoline or bromocriptine treats hyperprolactinaemia from a pituitary microadenoma and often restores menses.

  • Thyroid replacement

    Levothyroxine corrects hypothyroid-driven amenorrhoea and normalises the hypothalamic-pituitary-ovarian axis.

  • Surgical correction

    Hymenotomy, resection of a transverse vaginal septum and vaginal creation for MRKH restore outflow and reproductive potential.

  • Psychology and eating support

    Structured CAMHS or eating-disorder input for body image, disordered eating and educational stress is a core part of the plan.

  • Bone protection package

    DEXA monitoring, calcium and vitamin D, weight-bearing exercise and oestrogen replacement guard against low bone density.

What this guide is based on

The sources behind every claim on this page.

UK national guidance and specialist society standards, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your GP, paediatric endocrinologist or gynaecologist knows your child and can tell you which parts apply. If in doubt, get seen.

  • NICE. Amenorrhoea - clinical knowledge summary.

  • Royal College of Obstetricians and Gynaecologists (RCOG). Green-top guidance on amenorrhoea and menstrual disorders in adolescents.

  • British Society for Paediatric Endocrinology and Diabetes (BSPED). Guidance on delayed puberty and Turner syndrome.

  • European Society of Human Reproduction and Embryology (ESHRE). Guideline on premature ovarian insufficiency.

  • International Olympic Committee. Consensus statement on Relative Energy Deficiency in Sport (RED-S).

Red flags

When primary amenorrhoea needs urgent attention.

Most cases are worked up in outpatient paediatrics. These are the situations that need faster, specialist-led action.

  • Bulging, blue imperforate hymen

    Cyclical pain with a tense bluish bulge at the introitus is an obstructive emergency needing prompt gynaecology surgical review.

  • Sudden severe headache and visual loss

    A pituitary macroadenoma or apoplexy can present with amenorrhoea, headache, visual field loss and needs urgent imaging.

  • Very low BMI with bradycardia

    A severely underweight adolescent with a slow heart rate needs urgent medical stabilisation before outpatient work-up continues.

  • Signs of virilisation

    Deep voice, clitoromegaly or rapid hirsutism suggest an androgen-secreting tumour or CAH and warrant urgent endocrine review.

  • Turner syndrome features

    Short stature, webbed neck, cardiac murmur or renal anomaly with primary amenorrhoea needs karyotype and cardiology screening.

  • Suspected Swyer or AIS

    A 46,XY karyotype with a female phenotype requires specialist DSD care and consideration of gonadectomy for tumour risk.

  • Post-chemo or radiotherapy

    Amenorrhoea after gonadotoxic cancer treatment needs early endocrine review, fertility counselling and bone protection.

  • Safeguarding concerns

    Rapid weight loss, self-harm, disclosed abuse or coercive exercise regimes need safeguarding escalation alongside medical care.

  • Severe psychological distress

    Low mood, suicidal thoughts or body-image crisis linked to delayed puberty deserve urgent CAMHS or crisis support.

Living with it

A structured plan, with room to grow.

Four things that help most day to day. Fuel the body, protect the bones, keep the MDT close and think about future fertility early.

A quiet reminder

Adolescent care is a partnership.

Parents, patient and clinicians share the plan. Age-appropriate information, honest conversations and psychology support carry a family through the work-up.

  1. 01 Nourish

    Fuel the system

    Eating enough to match training and growth is the single biggest lever in functional hypothalamic amenorrhoea and RED-S.

  2. 02 Bones

    Protect the skeleton

    Oestrogen matters for bone. Calcium, vitamin D, weight-bearing exercise and, when indicated, HRT all pull in the same direction.

  3. 03 Follow-up

    Keep the MDT close

    Paediatric endocrine, gynaecology and psychology reviews at planned intervals keep the plan on track through puberty and beyond.

  4. 04 Future

    Talk about fertility early

    For Turner, POI, MRKH and Swyer syndromes, early fertility counselling opens options like egg or embryo storage and surrogacy.

Frequently asked

Everything we get asked about primary amenorrhoea.

Quick answers on definitions, common causes, RED-S, karyotype testing, HRT and imperforate hymen.

  • What counts as primary amenorrhoea?

    No menses by age 15 with normal secondary sexual characteristics, no menses by 13 without any secondary sexual characteristics, or no menses more than 3 years after breast development began. Any of those meets the definition and deserves evaluation.

  • What are the most common causes in UK adolescents?

    Functional hypothalamic amenorrhoea from low energy availability, PCOS, Turner syndrome, imperforate hymen and Mullerian agenesis (MRKH). Constitutional delay of puberty is a common cause of no menses by 13 in otherwise healthy girls with a family history.

  • How is RED-S different from a normal athlete pattern?

    Relative Energy Deficiency in Sport reflects too little energy for training plus growth. It suppresses GnRH, so periods stop, bone density drops, mood falls and performance plateaus. It is a medical diagnosis, not a badge of fitness, and needs nutritional restoration and reduced training load.

  • When is a karyotype needed?

    When FSH and LH are high with low oestradiol, when there is short stature with primary amenorrhoea, or when pelvic imaging shows an absent uterus. This picks up Turner syndrome (45,X), Swyer syndrome (46,XY DSD) and androgen insensitivity syndrome.

  • Why does the team offer HRT to a teenager?

    In hypogonadism such as Turner syndrome and POI, transdermal oestradiol with cyclical progesterone induces or completes puberty, protects bone density, supports uterine growth and stabilises mood. It is guided by paediatric endocrinology, not a lifestyle choice.

  • What happens if an imperforate hymen is not treated?

    Trapped menstrual blood collects behind the hymen (haematocolpos), causing worsening cyclical pain, urinary retention and, later, endometriosis. A simple hymenotomy performed by a paediatric or adolescent gynaecologist releases the obstruction and restores normal flow.

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