Disorders of Puberty

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Normal Puberty - Hormonal Harmony

  • HPG Axis Activation: Pulsatile GnRH ↑ → FSH/LH ↑ → gonadal steroidogenesis (estrogen/testosterone).
  • Adrenarche: ↑ adrenal androgens (DHEA, DHEAS) → pubic/axillary hair, body odor.
  • Sequence & Milestones:

    ⭐ Thelarche (breast development) is typically the first sign of puberty in girls, occurring between 8-13 years, followed by pubarche and then menarche.

    • Girls: Thelarche → Pubarche → Peak Height Velocity (PHV) → Menarche (10-15 yrs; ~2-3 yrs post-thelarche).
    • Boys: Testicular enlargement (≥4ml or 2.5cm; 9-14 yrs) → Pubarche → PHV → Spermarche. HPG Axis in Males and Females Tanner Stages of Pubertal Development Chart

Precocious Puberty - Too Soon Bloom

Puberty onset: Girls <8 yrs, Boys <9 yrs.

  • Central (CPP; GnRH-dependent): Premature HPG axis activation.
    • Diagnosis: Pubertal LH response to GnRH (peak LH >5-8 mIU/mL). Brain MRI needed.
    • Causes:
      • Idiopathic (common, esp. girls ~90%).
      • CNS lesions (boys > girls): Hypothalamic hamartoma, glioma, hydrocephalus.
  • Peripheral (PPP; GnRH-independent): Excess sex steroids; HPG axis suppressed.
    • Diagnosis: Prepubertal LH response to GnRH. Image adrenals/gonads.
    • Causes:
      • McCune-Albright Syndrome (MAS): PPP, café-au-lait spots, fibrous dysplasia.
      • Congenital Adrenal Hyperplasia (CAH).
      • Gonadal tumors (ovary, testis).
      • Adrenal tumors.
      • Exogenous steroids.
      • hCG-secreting tumors.

⭐ In girls with central precocious puberty, approximately 90% of cases are idiopathic, whereas in boys, an identifiable CNS pathology is much more common.

MRI showing hypothalamic hamartoma

Delayed Puberty - Late Bloomer Blues

  • Definition: No thelarche by age 13 in girls, or no testicular enlargement (≥4ml) by age 14 in boys.
  • Etiology:
    • Constitutional Delay of Growth & Puberty (CDGP): Most common, often familial. Bone age < chronological age.

      ⭐ Constitutional Delay of Growth and Puberty (CDGP) is the most common cause of delayed puberty, especially in boys, and is often associated with a positive family history.

    • Hypogonadotropic Hypogonadism (↓FSH, ↓LH - Central):
      • Kallmann Syndrome (anosmia, GnRH deficiency)
      • CNS tumors (e.g., craniopharyngioma), chronic illness, malnutrition
    • Hypergonadotropic Hypogonadism (↑FSH, ↑LH - Peripheral/Gonadal):
      • Turner Syndrome (45,XO): girls; short stature, webbed neck.
      • Klinefelter Syndrome (47,XXY): boys; tall, gynecomastia, small testes.
      • Gonadal dysgenesis, autoimmune oophoritis, chemo/radiotherapy. Phenotypic features of Klinefelter Syndrome
  • Diagnostic Approach:
  • Key Investigations: Bone age, FSH, LH, Estradiol/Testosterone, Karyotype.
  • Management: Treat underlying cause. Reassurance for CDGP. Hormone Replacement Therapy (HRT) if permanent hypogonadism.

Key Syndromes - Puberty Puzzles

SyndromeKaryotypeGonadsKey FeaturesHormones
Turner Syndrome45,X0Streak ovariesShort stature, webbed neck, shield chest, coarctation↑FSH, ↑LH, ↓Estrogen
Klinefelter Syndrome47,XXYTesticular dysgenesisTall, gynecomastia, small testes, infertility↓Testosterone, ↑FSH, ↑LH, ↑E2
Kallmann SyndromeVariableHypoplasticAnosmia/hyposmia, delayed puberty↓FSH, ↓LH (Hypogonadotropic Hypogonadism)
  • McCune-Albright Syndrome: Precocious puberty (GnRH-independent), café-au-lait spots (coast of Maine), polyostotic fibrous dysplasia. 📌 Triad: PPP (Precocious Puberty, Pigmentation, Polyostotic fibrous dysplasia).
  • Androgen Insensitivity Syndrome (AIS): 46,XY (genotype), female phenotype, absent uterus, testes present (often intra-abdominal), ↑Testosterone, ↑LH.

High‑Yield Points - ⚡ Biggest Takeaways

  • McCune-Albright syndrome: Characterized by precocious puberty, café-au-lait spots, and polyostotic fibrous dysplasia.
  • Kallmann syndrome: Presents with delayed puberty and anosmia/hyposmia due to GnRH deficiency.
  • Turner syndrome (45,XO): Features delayed puberty, streak gonads, and often primary amenorrhea.
  • Constitutional Delay (CDGP): Most common cause of delayed puberty in boys; bone age is delayed.
  • Central Precocious Puberty (CPP): Results from early HPG axis activation; treated with GnRH agonists.
  • Peripheral Precocious Puberty (PPP): GnRH-independent; caused by adrenal/gonadal tumors or CAH.
  • Isolated premature thelarche/adrenarche: Usually benign variants; require careful observation and reassurance.

Practice Questions: Disorders of Puberty

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Delayed puberty is seen in -

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Flashcards: Disorders of Puberty

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In polycystic ovarian syndrome, excess androgen (from theca cells) is converted to _____ in adipose tissue, which inhibits FSH secretion from anterior pituitary

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In polycystic ovarian syndrome, excess androgen (from theca cells) is converted to _____ in adipose tissue, which inhibits FSH secretion from anterior pituitary

estrone

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