Causes of delayed Onset of Puberty in Children ✅

⚠️ Delayed puberty means puberty has not started by the expected age. In UK practice, this usually means no breast development by 13 years in girls or no testicular enlargement by 14 years in boys. In girls, delayed puberty / pubertal assessment is also needed if menstruation has not started by 15 years despite secondary sexual characteristics.

📖 About

• Puberty results from activation of the hypothalamic-pituitary-gonadal (HPG) axis.
• Pulsatile GnRH stimulates LH and FSH, which then stimulate gonadal sex steroid production.
• Delayed puberty is a common paediatric endocrine referral and is more common in boys.
• The commonest cause, especially in boys, is constitutional delay of growth and puberty (CDGP).

🧬 Main causes

• Constitutional delay of growth and puberty (CDGP) – often familial, with delayed bone age and otherwise normal health.
• Functional hypogonadotropic hypogonadism – chronic disease, undernutrition, eating disorder, excessive exercise, or psychosocial stress.
• Permanent hypogonadotropic hypogonadism – for example Kallmann syndrome, pituitary/hypothalamic disorders, tumour, trauma, radiotherapy.
• Primary gonadal failure / hypergonadotropic hypogonadism – for example Turner syndrome or Klinefelter syndrome.
• Other endocrine causes include hypothyroidism and hyperprolactinaemia.

🩺 Key assessment points

• Plot height, weight, BMI, and growth velocity on growth charts.
• Ask whether puberty is absent, slow, or arrested.
• Ask about family history of late puberty.
• Screen for chronic disease, weight loss, eating disorder, excessive exercise, systemic symptoms, CNS symptoms, and previous surgery/radiotherapy.
• Ask specifically about anosmia (suggesting Kallmann syndrome).
• Examine for Tanner stage, dysmorphic features, and signs of chronic illness.

🔎 Investigations

• 📸 Bone age X-ray – often delayed in CDGP and useful alongside growth assessment.
• 🧪 Hormones: LH, FSH, testosterone in boys / oestradiol in girls.
• 🧪 TSH and free T4.
• 🧪 Prolactin if clinically indicated.
• 🧪 Screening for chronic disease where relevant: for example FBC, ESR/CRP, renal/liver profile, coeliac screen.
• 🧬 Karyotype if Turner syndrome, Klinefelter syndrome, or primary gonadal failure is suspected.
• 🧠 MRI pituitary/hypothalamus if there are neurological symptoms, multiple pituitary deficits, or suspected permanent central hypogonadism.

👩 Girls – referral / red flags

• ❌ No breast development by 13 years.
• ❌ No menarche by 15 years despite pubertal development.
• ❌ No menarche by 13 years with no secondary sexual characteristics.
• ❌ Marked short stature, Turner features, galactorrhoea, headaches, visual symptoms, or evidence of chronic disease.

👦 Boys – referral / red flags

• ❌ No testicular enlargement (testicular volume <4 mL) by 14 years.
• ❌ Falling growth velocity or significant short stature.
• ❌ Neurological symptoms, anosmia, previous testicular injury/torsion, or evidence of systemic illness.
• ❌ Pubertal arrest or failure to progress once puberty has started.

📊 Tanner staging (high-yield)

• 👩 Girls: breast development is the key marker of gonadarche.
• 👦 Boys: testicular enlargement is the first true sign of puberty.
• 👥 Pubic hair alone is not a reliable marker of true pubertal onset, because adrenarche can occur separately from gonadal puberty.

📈 Normal sequence

• 👩 Girls: breast development usually starts first, then pubertal growth acceleration, with menarche later.
• 👦 Boys: testicular enlargement occurs first, followed by pubic hair, penile growth, and then later peak growth spurt.

🧾 Causes of delayed puberty

📝 Summary

Delayed puberty should prompt assessment of growth pattern, Tanner stage, family history, chronic illness, nutrition, and hormone profile. 👩 Girls: think delayed puberty if no breasts by 13 or no menarche by 15. 👦 Boys: think delayed puberty if testicular volume remains <4 mL by 14. The commonest cause is constitutional delay, but always exclude chronic disease, central hypogonadism, and primary gonadal failure.

📚 References

• NHS: Early or delayed puberty
• NICE CKS: Primary amenorrhoea – management
• Kingston & Richmond NHS: Delayed puberty referral guidance
• NHS Lothian RefHelp: Delayed puberty in girls
• BSPED / RCPCH: UK standards for paediatric endocrinology (2024 update)

Clinical cases

• 🧬 Case 1 – Age 15: Boy with no testicular enlargement, mild short stature, normal growth velocity, delayed bone age, and father who “started late”. Diagnosis: Constitutional delay of growth and puberty. Teaching point: Delayed bone age with preserved growth potential and family history strongly supports CDGP.
• 🩺 Case 2 – Age 13: Girl with no breast development and anosmia. Diagnosis: Hypogonadotropic hypogonadism, with Kallmann syndrome an important possibility. Teaching point: Low gonadotropins plus anosmia is a classic clue to defective GnRH neuron migration.
• 💢 Case 3 – Age 14: Girl with short stature, webbed neck, no breast development, and high LH/FSH. Diagnosis: Turner syndrome. Teaching point: High gonadotropins with low sex steroids point to primary ovarian failure.