Puberty and Its Disorders

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Normal Puberty - The Hormone Symphony

Puberty: A neuroendocrine cascade driven by pulsatile Gonadotropin-Releasing Hormone (GnRH) from the hypothalamus. Influenced by genetics, nutrition (Leptin: permissive), and Kisspeptin.

  • Core Pathway (Gonadarche):
    • Hypothalamus: Pulsatile GnRH release.
    • Anterior Pituitary: Secretes LH & FSH.
    • Gonads (Ovaries/Testes): Produce sex steroids (Estrogen-♀ / Testosterone-♂) under LH/FSH stimulation.
    • Effects: Development of secondary sexual characteristics, growth spurt, achievement of fertility.
  • Adrenarche:
    • Separate adrenal androgen (DHEA, DHEAS) surge around 6-8 years.
    • Contributes to pubic/axillary hair (pubarche), body odor, acne.

HPG axis hormonal cascade

⭐ The first sign of puberty in girls is thelarche (breast budding); in boys, it's testicular enlargement (≥ 4ml or > 2.5cm length).

Precocious Puberty - Early Bloomers

  • Definition: Onset of secondary sexual characteristics before age 8 in girls, 9 in boys.
  • Types:
    • Central (GnRH-dependent): Premature activation of Hypothalamic-Pituitary-Gonadal (HPG) axis.
      • Idiopathic (most common, esp. girls).
      • CNS lesions: Hamartoma (most common tumor), astrocytoma, hydrocephalus.
    • Peripheral (GnRH-independent): Excess sex steroids from gonads, adrenals, or exogenous sources.
      • Girls: Ovarian cysts/tumors.
      • Boys: Leydig cell tumors, Congenital Adrenal Hyperplasia (CAH), HCG-secreting tumors.
      • McCune-Albright Syndrome (MAS).
  • Incomplete variants: Premature thelarche, premature adrenarche/pubarche.
  • Diagnosis:
    • Advanced bone age (X-ray hand/wrist).
    • GnRH stimulation test: Differentiates Central (LH surge) from Peripheral (suppressed LH). Peak LH >5-8 IU/L; LH/FSH ratio >0.6.
    • Pelvic/Testicular USG. Brain MRI for Central PP (esp. boys & girls <6 yrs).
  • Treatment:
    • Central: GnRH analogs (e.g., Leuprolide).
    • Peripheral: Address underlying cause.

⭐ McCune-Albright Syndrome triad:

  1. Peripheral precocious puberty.
  2. Café-au-lait macules (irregular "coast of Maine" border).
  3. Polyostotic fibrous dysplasia.

X-ray left hand and wrist with bone age overlay

Delayed Puberty - Late to the Party

  • Definition:
    • Girls: No breast development (thelarche) by 13 years; no menarche by 16 years or >5 years after thelarche.
    • Boys: No testicular enlargement (testicular volume <4 mL or longest diameter <2.5 cm) by 14 years.
  • Most common: Constitutional Delay of Growth & Puberty (CDGP) - "late bloomers"; delayed bone age, positive family history.
  • Classification & Key Causes:
    • Hypogonadotropic Hypogonadism (Central; ↓FSH/LH):
      • Functional: Chronic illness, malnutrition, hypothyroidism, intense exercise.
      • Congenital: Kallmann syndrome (anosmia), Prader-Willi.
      • Acquired: CNS tumors (e.g., craniopharyngioma).
    • Hypergonadotropic Hypogonadism (Primary Gonadal Failure; ↑FSH/LH):
      • Girls: Turner syndrome (45,XO).
      • Boys: Klinefelter syndrome (47,XXY).
      • Other: Gonadal dysgenesis, post-chemo/radiation.
  • Initial Evaluation: History, exam (Tanner staging), bone age. Then FSH, LH, Estradiol/Testosterone.

⭐ Kallmann syndrome: Defective GnRH neuron migration leading to hypogonadotropic hypogonadism and anosmia/hyposmia. Often KAL1 gene mutation.

GnRH neuron migration defect in Kallmann syndrome

High‑Yield Points - ⚡ Biggest Takeaways

  • Tanner staging is crucial for pubertal assessment.
  • Precocious puberty: onset <8 years (girls), <9 years (boys).
  • Delayed puberty: no signs by 13 years (girls), 14 years (boys).
  • McCune-Albright syndrome: triad of precocious puberty, café-au-lait spots, polyostotic fibrous dysplasia.
  • Kallmann syndrome: hypogonadotropic hypogonadism plus anosmia.
  • Constitutional delay (CDGP): most common cause of delayed puberty in boys.
  • Central precocious puberty is GnRH-dependent; peripheral is GnRH-independent.

Practice Questions: Puberty and Its Disorders

Test your understanding with these related questions

A child with decreased levels of LH, FSH and Testosterone presents with delayed puberty. Which of the following is the most likely Diagnosis

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Flashcards: Puberty and Its Disorders

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_____ commonly presents in 12-18 year olds with sudden testicular pain, high-riding testis, and absent cremasteric reflex

TAP TO REVEAL ANSWER

_____ commonly presents in 12-18 year olds with sudden testicular pain, high-riding testis, and absent cremasteric reflex

Testicular torsion

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