Causes of delayed Onset of Puberty in Children

⚠️ Delayed Puberty is defined as onset of puberty later than expected. In the UK: > 13 years in girls and > 14 years in boys. Improved nutrition and rising obesity are linked to earlier onset of puberty, so delays stand out more.

📖 About

• Puberty = activation of the hypothalamic–pituitary–gonadal (HPG) axis.
• Driven by pulsatile GnRH → ↑ LH & FSH → sex steroid release.
• Delayed puberty = > 2.5 SD above population mean for onset.

🧬 Aetiology

• Functional hypogonadotrophic hypogonadism (chronic illness, malnutrition, steroids).
• Endocrine disorders: hypothyroidism, hyperprolactinaemia.
• Genetic syndromes: Turner, Klinefelter, Kallmann.

🔍 Investigations

• 📸 Bone age X-ray: >2 years delay vs chronological age suggests pathology.
• 🧪 Labs: LH, FSH, testosterone/estradiol, TSH/T4, prolactin.
• 💉 Alkaline phosphatase often elevated during bone growth.

👩 Girls – Red Flags

• ❌ No breast development by 14.
• ❌ No pubic hair by 14.
• ❌ > 5 years between start and completion of breast development.
• ❌ No menarche by 16.

👦 Boys – Red Flags

• ❌ No testicular enlargement (> 2.5 cm) by 14.
• ❌ No pubic hair by 15.
• ❌ > 5 years between start and completion of genital development.

📊 Tanner Staging (Highlights)

• 👩 Breasts (B1–B5): From papilla only ➝ mature breast.
• 👦 Genitalia (G1–G5): From prepubertal ➝ adult penis & testes.
• 👥 Pubic hair (P1–P5): From none ➝ adult distribution on thighs.

📈 Normal Sequence

• 👩 Girls: Thelarche (~11y) ➝ growth spurt ➝ menarche (~12–13y). Full breast development: 4 yrs, pubic hair: 2.5 yrs.
• 👦 Boys: Testicular enlargement (~11.5y) ➝ pubic hair ➝ penile growth ➝ growth spurt (~Tanner 4–5).

🧾 Causes of Delayed Puberty

📝 Summary

Delayed puberty is a common referral in paediatrics and endocrinology. 👩 Girls: no breasts by 14, no menarche by 16. 👦 Boys: no testicular enlargement by 14. Causes range from constitutional delay (commonest) ➝ hypogonadism ➝ systemic illness. ✅ Always check growth, bone age, hormones, and look for underlying chronic disease.

Clinical cases

• 🧬 Case 1 – Age 15 (Constitutional Delay of Growth and Puberty): Boy referred for lack of secondary sexual characteristics. Height on the 10th centile; father reported late puberty at 16. Bone age delayed by 2 years; LH, FSH, and testosterone all low-normal. Diagnosis: Constitutional delay of growth and puberty (CDGP). Management: Reassurance, monitoring of growth velocity, and short course of low-dose testosterone if significant psychosocial distress. Teaching point: CDGP is the commonest cause of delayed puberty, especially in boys — normal variant of development with family history of “late bloomers.”
• 🩺 Case 2 – Age 13 (Hypogonadotrophic Hypogonadism): Girl with no breast development or menarche. Normal height but anosmia noted on history. Hormones: low LH/FSH and oestradiol. MRI showed absent olfactory bulbs. Diagnosis: Kallmann syndrome (failure of GnRH neuronal migration). Management: Hormone replacement with oestrogen (then progesterone added later) and long-term endocrinology follow-up. Teaching point: Low gonadotrophins with low sex steroids suggest central (hypothalamic/pituitary) causes — Kallmann syndrome is a classic example.
• 💢 Case 3 – Age 14 (Hypergonadotrophic Hypogonadism): Girl with short stature and no breast or pubic hair development. Webbed neck, widely spaced nipples, and low hairline on examination. LH and FSH markedly elevated. Diagnosis: Turner syndrome (45,X karyotype). Management: Oestrogen replacement for puberty induction, growth hormone therapy, and screening for cardiac and renal anomalies. Teaching point: High gonadotrophins with low sex hormones point to primary gonadal failure — Turner syndrome is the most common chromosomal cause in females.