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Health condition · Clinically reviewed

Delayed puberty, causes, careful assessment - and a considered plan.

Most delayed puberty is a normal variant that resolves on its own. A small but important group need specialist endocrine care - and clarity early on protects both growth and fertility.

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Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a UK-registered clinician before publication.

  • 02

    Sourced from guidance

    Checked against BSPED, NICE and peer-reviewed adolescent endocrine sources listed at the end.

  • 03

    Current for 2026

    Reflects modern UK paediatric and adolescent endocrine practice, including fertility preservation and transition care.

Key facts

Delayed puberty at a glance.

The essentials, in plain English - the definitions, the main causes and how UK specialists approach assessment and treatment.

  • What it is

    Absence of pubertal onset by age 13 in girls (no breast development) or age 14 in boys (testicular volume under 4 mL).

  • How common

    Around 2 to 3 per cent of adolescents. Constitutional delay is more common in boys than girls.

  • Most common cause

    Constitutional delay of growth and puberty (CDGP) - a familial, normal variant. Around 65 per cent of boys, 30 per cent of girls presenting.

  • Central causes

    Hypogonadotrophic hypogonadism - Kallmann, isolated GnRH deficiency, chronic disease, eating disorder, brain tumour.

  • Primary gonadal

    Hypergonadotrophic hypogonadism - Turner syndrome, Klinefelter syndrome, gonadal dysgenesis, chemo or radiation damage.

  • Care setting

    Specialist paediatric and adolescent endocrinology, with fertility, genetics and psychology input as needed.

Why this guide matters

A specialist question, not a wait-and-see one.

Most young people with delay are ultimately reassured. Getting the assessment right protects the ones who aren't - and reduces distress for everyone.

  • CDGP is common - and treatable

    Constitutional delay is the single most common cause, especially in boys. Short, low-dose hormone courses can help those finding the wait very difficult.

  • Hidden causes need excluding

    Chronic disease, eating disorder, brain tumour and chromosomal conditions can all present as delay. Bloods, bone-age and, where needed, MRI and karyotype find them.

  • Fertility deserves an early plan

    For Turner, Klinefelter or gonadotoxic exposure, discussing fertility preservation early opens options that close later.

How the diagnosis is made

From first concerns to a clear plan.

The steps a UK paediatric or adolescent endocrine team will normally follow, in order - so you know what to expect and why.

  1. 01

    Assessing

    History and family pattern

    Parental puberty timing, family history, chronic illness, medications, nutrition, exercise load and eating pattern all matter.

  2. 02

    Assessing

    Examination and Tanner staging

    Height, weight, BMI, growth chart, Tanner stage and testicular volume by Prader orchidometer. Screen for dysmorphic features of Turner or Klinefelter.

  3. 03

    Assessing

    Bone age X-ray

    Left-wrist film. Bone age is usually delayed in CDGP and in hypogonadism, which helps separate them from short stature alone.

  4. 04

    Confirming

    Endocrine and general bloods

    LH, FSH, oestradiol or testosterone, prolactin, TSH, free T4, IGF-1, FBC, U and Es, LFTs and coeliac serology.

  5. 05

    Confirming

    Karyotype and genetics

    Karyotype when Turner or Klinefelter is suspected. Targeted genes (FGFR1, KAL1, PROK2 and others) for suspected Kallmann or isolated GnRH deficiency.

  6. 06

    Confirming

    Imaging and olfactory testing

    MRI of the pituitary and hypothalamus for suspected central causes. Formal olfactory testing when Kallmann syndrome is on the list.

  7. 07

    Planning

    Specialist referral

    Paediatric and adolescent endocrinology lead the plan, with fertility, genetics and psychology alongside.

Typical timeline: first assessment to a working plan in weeks, with structured follow-up over months.

Presentation

What delayed puberty looks like.

The classic patterns - absent or stalled puberty, growth concerns and the features that point towards a specific underlying cause.

  • No breast development by 13

    In girls, absent thelarche by age 13 is the classic threshold for further assessment.

  • No testicular enlargement by 14

    In boys, testicular volume under 4 mL by age 14 is the standard trigger for endocrine review.

  • No menarche by 15 or 16

    Primary amenorrhoea by 15 to 16, or five years after breast development, warrants endocrine and gynaecological work-up.

  • Arrested puberty

    Puberty starts, then stalls. Progress should be steady over 2 to 4 years - a halt is not normal and needs review.

  • Short stature or slow growth

    Falling growth velocity or crossing centiles on the growth chart alongside pubertal delay is a red flag.

  • Anosmia or hyposmia

    Reduced or absent sense of smell alongside delay strongly suggests Kallmann syndrome.

  • Body-image and mood impact

    Delay is often psychologically difficult - looking younger than peers, bullying and low mood are common and deserve support.

  • Red flag - dysmorphic features

    Turner (webbed neck, short stature, cubitus valgus) or Klinefelter (tall stature, small firm testes) features need urgent karyotype.

Treatment

How delayed puberty is treated in the UK.

A stepped plan - reassurance and monitoring for CDGP, sex-steroid replacement for hypogonadism, and treatment of the underlying cause where one exists. Fertility and psychological support run through the whole pathway.

  • Reassurance and monitoring

    For clear-cut CDGP - watchful waiting with growth and puberty tracking every 4 to 6 months, plus psychological support.

  • Short course testosterone (boys)

    Low-dose testosterone (typically 50 to 100 mg IM monthly for 3 to 6 months) can kick-start puberty in CDGP - specialist-led.

  • Low-dose oestradiol (girls)

    Very low-dose oestradiol can induce breast development in CDGP or hypogonadism - specialist-titrated and monitored.

  • Full sex-steroid replacement

    Girls - gradually increasing oestradiol, then progestogen once breakthrough bleeding starts. Boys - gradually increasing testosterone to adult dose.

  • Treat the underlying cause

    Optimise coeliac, IBD, CKD or thyroid disease. Support eating-disorder recovery. Address hyperprolactinaemia or Cushing syndrome.

  • Growth hormone

    Licensed in Turner syndrome and selected other indications - specialist paediatric endocrine decision.

  • Fertility preservation

    Oocyte, ovarian tissue or testicular tissue cryopreservation before gonadotoxic therapy - specialist reproductive endocrine input.

  • Transition to adult endocrine

    Structured handover in late adolescence, with lifelong sex-steroid replacement, bone health, fertility and comorbidity review.

MDT care

A multidisciplinary approach for a complex diagnosis.

Paediatric and adolescent endocrinology work alongside clinical genetics, fertility, gynaecology, urology, adolescent psychology and, where relevant, oncology and neurosurgery. Many patients are seen in specialist commissioned services and later transition to adult endocrine care.

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, paediatrician or endocrinologist knows the full history and can say which parts apply. If in doubt, seek review.

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

  • NICE Clinical Knowledge Summaries. Amenorrhoea and pubertal disorders.

  • European Society for Paediatric Endocrinology. Consensus on constitutional delay and hypogonadotrophic hypogonadism.

  • Royal College of Paediatrics and Child Health. Growth chart guidance and bone-age assessment standards.

Red flags

When delay needs urgent attention.

Not every delayed puberty is a normal variant. These are the features that push the case to specialist review or urgent imaging.

  • Suspected intracranial cause

    Headaches, visual-field loss, morning vomiting or new endocrine features alongside pubertal delay need urgent MRI - see the craniopharyngioma guide.

  • Turner syndrome features

    Short stature, webbed neck, wide-spaced nipples, lymphoedema or cardiac features - urgent karyotype and cardiology review.

  • Klinefelter syndrome features

    Tall stature, small firm testes, gynaecomastia or learning differences in a boy with delay - karyotype and endocrine review.

  • Eating disorder or excess exercise

    Very low BMI, restrictive eating or heavy training with pubertal delay - urgent adolescent-medicine and mental-health input.

  • Chronic disease

    Unexplained weight loss, chronic diarrhoea, fatigue or growth failure - screen for coeliac, IBD, CKD, thalassaemia and cystic fibrosis.

  • Anosmia with delay

    Reduced or absent sense of smell strongly suggests Kallmann syndrome - MRI olfactory bulbs and genetic panel.

  • Hyperprolactinaemia

    Galactorrhoea, headaches or visual symptoms - measure prolactin and image the pituitary.

  • History of chemotherapy or pelvic radiotherapy

    Gonadal damage is common - baseline gonadal function and early fertility discussion are essential.

  • Psychological crisis

    Severe body-image distress, self-harm or suicidal ideation deserves urgent CAMHS or crisis assessment alongside endocrine care.

Living with it

A quiet, patient plan - with room for real support.

Four things that make the biggest difference - understanding the diagnosis, having psychological support, protecting bone health and planning for fertility.

A quiet reminder

A slower start is not a smaller life.

Most young people with delayed puberty go on to normal adult health, height and fertility. Where they don't, modern endocrine care can do a great deal.

  1. 01 Framing

    CDGP is a normal variant

    Most young people with constitutional delay will go through normal puberty and reach a normal adult height - the wait is the hardest part.

  2. 02 Support

    Psychological support counts

    Looking younger than peers can be tough. Adolescent psychology and peer support help as much as any medicine.

  3. 03 Bone

    Look after bone health

    Calcium, vitamin D, weight-bearing activity and, where indicated, DEXA scans protect adult bone density.

  4. 04 Fertility

    Plan for fertility early

    For Turner, Klinefelter or gonadotoxic exposure, discuss fertility preservation and options (including donor gametes) before treatment escalates.

Frequently asked

Everything we get asked about delayed puberty.

Quick answers on definitions, causes, assessment, treatment and fertility.

  • What counts as delayed puberty?

    No breast development in a girl by age 13, or a testicular volume under 4 mL in a boy by age 14. Absent menarche by 15 to 16, or puberty that starts and then stalls, also counts and deserves assessment.

  • What is the most common cause?

    Constitutional delay of growth and puberty (CDGP) - a familial, normal variant. It accounts for around 65 per cent of boys and 30 per cent of girls presenting with delay. Bone age is delayed and puberty eventually progresses normally.

  • How is delayed puberty investigated?

    A full history and examination with Tanner staging, a bone-age X-ray, endocrine bloods (LH, FSH, oestradiol or testosterone, prolactin, thyroid), general bloods (coeliac serology, FBC, U and Es, LFTs) and, where indicated, karyotype, MRI pituitary and olfactory testing.

  • Is treatment always needed?

    Not always. Many young people with CDGP need only reassurance and monitoring. A short course of low-dose testosterone or oestradiol can help those who find the wait very distressing or when growth is a concern.

  • What about fertility?

    It depends on the cause. CDGP does not affect fertility. Hypogonadotrophic hypogonadism often responds to gonadotrophin therapy when fertility is wanted. Turner and Klinefelter syndromes usually cause infertility - early fertility preservation and donor gametes should be discussed with a specialist.

  • Who looks after delayed puberty in the UK?

    Specialist paediatric and adolescent endocrinology teams lead care, with input from clinical genetics, fertility, adolescent psychology and, where relevant, gynaecology and urology. Care transitions to adult endocrine services in late adolescence.

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