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Puberty: Normal and Abnormal - Detailed Notes

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PART 1: NORMAL PUBERTY

1.1 Definition

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1.2 Two Key Physiological Processes

• Physical and functional maturation of the gonads
• Gonads begin producing gametes and sex steroids
• Driven by rising FSH and LH from the anterior pituitary
• In males: leads to spermarche (initiation of sperm production)
• In females: leads to folliculogenesis, thelarche (breast development), and menarche (first menstrual period)

• Increased production of adrenal androgens: DHEA, DHEAS, and androstenedione (A4) by the adrenal cortex
• Peculiar to humans and great apes; occurs in both sexes during prepuberty (ages 6-8 years)
• Induces pubarche (growth of pubic and axillary hair)
• Adrenarche begins at age 8-10 in girls and 10-12 in boys
• DHEA peaks at ~age 25 in women, slightly later in men, then declines
• Absence of adrenarche does NOT prevent gonadarche or reproductive competence

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1.3 Hormonal Axis - Control of Puberty

• The hypothalamus contains GnRH neurons controlled by higher brain centers integrating multiple physiological signals
• Before puberty: GnRH and gonadotropin levels are low because the HPG axis is highly sensitive to negative feedback by gonadal steroids - even low levels of sex steroids suffice to suppress LH/FSH
• At puberty onset: sensitivity of the HPG axis to negative feedback DECREASES, allowing GnRH pulsatility to emerge
• Earliest event of puberty = onset of pulsatile GnRH release during REM sleep, which gradually extends throughout the day
• Rising FSH and LH from the pituitary then stimulate gonadarche

• Kisspeptin (KISS1) and its receptor (KISS1R) - positive regulators
• MKRN3 (makorin ring finger protein 3) - inhibitory; mutations cause early puberty
• TAC3, TACR3 - regulate GnRH secretion
• Congenital defects in GnRH neuron migration: ANOS1, PROK2, FGFR1, FGF8, CHD7

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1.4 Timing of Normal Puberty

• Puberty age has been declining in developed countries at 1-3 months per decade for over 175 years
• Adrenarche is the first step (ages 6-10); gonadarche follows

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1.5 Tanner Stages

TANNER STAGES - GIRLS (Breast + Pubic Hair)

TANNER STAGES - BOYS (Genitalia + Pubic Hair)

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1.6 Sequence of Pubertal Events

1. Adrenarche / pubarche (age 6-8)
2. Thelarche - breast bud development (first sign of gonadarche, ~age 10-11)
3. Pubic and axillary hair
4. Growth spurt (peak at Tanner 3, ~12.5 yr)
5. Menarche (Tanner 4, ~13.3 yr) - initial cycles typically anovulatory
6. Regular ovulatory cycles (~1 year after menarche)

1. Adrenarche / pubarche (age 8-10)
2. Testicular enlargement (first sign, ~age 11-12)
3. Penile growth
4. Pubic, axillary, facial hair
5. Voice change and gynecomastia (Tanner 3)
6. Growth spurt (peak at Tanner 4, ~13.8 yr - later than girls)
7. Spermarche

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PART 2: ABNORMAL PUBERTY

2.1 Overview - Evaluation Triggers

• Signs of puberty in girls younger than 8 years (White) or younger than 6 years (Black)
• Signs of puberty in boys younger than 9 years
• Absence of thelarche by age 12 years in girls
• Absence of testicular enlargement by age 14 years in boys
• Duration between thelarche and menarche >5 years

• Detailed history (growth/developmental milestones, medications, diet, family history, ethnicity)
• Physical examination with Tanner staging
• Growth chart from birth to present
• Left wrist X-ray for bone age
• If true precocious puberty suspected: cranial CT or MRI to rule out CNS lesions

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PART 3: PRECOCIOUS PUBERTY

3.1 Definition

• Girls: before age 8 (White), before age 6 (Black)
• Boys: before age 9 (all races)
• Boys: progressive testicular enlargement >4 mL before 9 years with linear growth acceleration and advanced bone age

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3.2 Classification

• Isosexual precocity: Signs consistent with the child's own gender (e.g., feminization of a girl, virilization of a boy)
• Heterosexual (contrasexual) precocity: Signs consistent with the opposite gender (e.g., virilization of a girl, breast development in a boy)
• Progressive: Advances one Tanner stage every 3-6 months
• Nonprogressive: No progression of pubertal signs over time

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3.3 Central (GnRH-Dependent) Precocious Puberty

• Idiopathic (most common, especially in girls) - no identifiable cause
• CNS lesions:
  • Hypothalamic hamartoma (most common organic cause)
  • Optic glioma, astrocytoma, ependymoma
  • Arachnoid cysts
  • Tuberous sclerosis
  • Inflammatory/infectious lesions
• Genetic mutations: KISS1 (kisspeptin), KISS1R, MKRN3 gain/loss-of-function
• Primary hypothyroidism (severe, prolonged - can trigger central precocity)
• After androgen exposure
• Post-cranial irradiation

• FSH, LH, prolactin, sex steroids, TSH
• Morning testosterone (boys)
• GnRH-agonist stimulation test (females)
• MRI brain - mandatory to rule out CNS pathology, especially in boys

• GnRH agonists (e.g., leuprolide): reversibly inhibit gonadotropin secretion
  • Prevent further secondary sexual development
  • Prevent early epiphyseal fusion (preserves final adult height)
  • Optimal age to discontinue: 11 years; puberty resumes normally after
• Treat underlying CNS lesion if present
• Slowly progressive cases may be managed with observation only

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3.4 Peripheral (GnRH-Independent) Precocious Puberty

• McCune-Albright syndrome (activating GNAS1 mutation → autonomous gonadal steroidogenesis)
• Adrenal disorders:
  • Congenital adrenal hyperplasia (CAH) - most common in girls presenting with virilization
  • Adrenal tumors (androgen or estrogen producing)
• Exogenous sex steroid exposure (estrogen creams, medications)
• hCG-secreting tumors (germ cell tumors)

• Activating LH receptor mutations - familial male-limited precocious puberty (testotoxicosis)
• Testicular tumors (Leydig cell, Sertoli cell)

• Café-au-lait spots (irregular "coast of Maine" borders)
• Polyostotic fibrous dysplasia
• Peripheral precocious puberty (autonomous gonadal activation)

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3.5 Benign Variants / Incomplete Precocious Puberty

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3.6 Long-Term Consequences of Precocious Puberty

• Shorter final adult height (early epiphyseal fusion)
• Increased risk of breast and endometrial cancer (earlier estrogen exposure)
• Cardiovascular disease, hypertension, type 2 diabetes
• Psychosocial issues (early physical maturity in young children)
• Shorter lifespan

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PART 4: DELAYED PUBERTY

4.1 Definition

• Boys: No testicular enlargement by age 14 years OR more than 5 years between initial and complete genital development (up to age 19)
• Girls: No thelarche by age 12 years OR more than 5 years between thelarche and menarche (by age 17)
• Represents 2-2.5 standard deviations above the mean onset age

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4.2 Classification and Causes

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4.3 Self-Limited (Constitutional) Delay

• Most common cause (~60% of boys, ~30% of girls with delayed puberty)
• Diagnosis of exclusion
• Mechanism: delayed GnRH pulse generation → low gonadotropins
• Height and weight below 5th percentile but catch up during adolescence
• Normal adult height and weight typically achieved
• Family history of delayed puberty in one or both parents (autosomal dominant in some families; X-linked or bilineal in others)
• Lab values remain prepubertal until puberty eventually begins
• FSH, LH, DHEA-S, prolactin, testosterone, estradiol: all prepubertal

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4.4 Functional Hypogonadotropic Hypogonadism

• Anorexia nervosa / eating disorders
• Excessive weight loss or low body fat
• Extreme exercise (e.g., competitive female athletes, long-distance runners)
• Chronic disease (inflammatory bowel disease, celiac disease, renal failure, etc.)
• Malnutrition
• Head trauma
• CNS tumors and treatment (radiotherapy, surgery)
• Infiltrative diseases (hemochromatosis, sarcoidosis, histiocytosis)
• Infections

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4.5 Permanent Hypogonadotropic Hypogonadism

• Kallmann syndrome = congenital HH + anosmia (failure of GnRH neuron migration from olfactory placode)
• 10-20% of those with congenital HH may experience spontaneous restoration of GnRH secretion in adulthood

• Pituitary tumors (craniopharyngioma, prolactinoma)
• Post-irradiation
• Trauma, surgery
• Panhypopituitarism - presents with delayed puberty + growth failure + hypothyroidism + adrenal insufficiency

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4.6 Primary Gonadal Failure (Hypergonadotropic Hypogonadism)

• Turner syndrome (45,X) - most common cause of hypergonadotropic hypogonadism in girls
• Autoimmune oophoritis
• Chemotherapy/irradiation
• Gonadal dysgenesis

• Klinefelter syndrome (47,XXY) - most common
• Bilateral cryptorchidism (untreated)
• Orchitis (viral - mumps)
• Chemotherapy/irradiation
• Anorchia

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4.7 Evaluation of Delayed Puberty

• Growth patterns since birth
• Presence of any secondary sexual development
• Diet and exercise habits
• Systemic illnesses
• Neurologic symptoms (headaches, visual changes)
• Family history of delayed puberty
• Psychosocial history

• Height, weight, arm span (arm span >5 cm above height suggests eunuchoid configuration - delayed epiphyseal closure from hypogonadism)
• Visual fields
• Hair growth pattern, testicular volume, phallic size, scrotal reddening
• Tanner staging

• Bone age (left wrist X-ray) - delayed in constitutional delay
• CBC, ESR, liver function tests
• FSH, LH, testosterone/estradiol, DHEA-S, prolactin

• MRI pituitary/hypothalamus if hypogonadotropic HH suspected
• Karyotype if Turner or Klinefelter suspected
• GnRH stimulation test to differentiate constitutional delay from permanent HH (though not perfectly discriminatory)

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4.8 Treatment of Delayed Puberty

• Reassurance is appropriate for many - puberty will occur eventually
• Consider impact on social relationships and school performance
• Boys: If treatment desired:
  • Testosterone enanthate or cypionate 25-50 mg IM every 2-4 weeks
  • OR testosterone patch 2.5 mg / testosterone gel 25 mg
  • Interrupt after 6 months to check if endogenous puberty has started
  • Consider aromatase inhibitors co-administration to improve final height (testosterone aromatizes to estrogen which drives epiphyseal closure)
• Girls: Low-dose estrogen to initiate puberty

• Earlier hormone treatment required
• Boys: hCG therapy to induce testicular development and spermatogenesis
• Long-term testosterone replacement
• For fertility: pulsatile GnRH therapy or gonadotropin therapy (FSH + hCG)

• Long-term sex hormone replacement
• Turner syndrome: estrogen replacement + GH therapy
• Klinefelter: testosterone replacement

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PART 5: SUMMARY TABLE - ABNORMAL PUBERTY AT A GLANCE

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PART 6: CLINICAL PEARLS

1. First sign of puberty in girls: Breast bud development (thelarche) - Tanner stage 2
2. First sign of puberty in boys: Testicular enlargement >2.5 cm - Tanner stage 2
3. Girls reach peak growth velocity at Tanner stage 3 (~8 cm/yr); boys at Tanner stage 4 (~10 cm/yr)
4. Gonadotropin pattern distinguishes primary from secondary gonadal failure - high gonadotropins = primary gonadal failure
5. Kallmann syndrome = HH + anosmia (smell should always be tested in delayed puberty)
6. GnRH agonists paradoxically suppress puberty because continuous (non-pulsatile) GnRH downregulates pituitary receptors
7. Children with developmental disabilities have higher incidence of precocious puberty
8. McCune-Albright = café-au-lait + polyostotic fibrous dysplasia + peripheral precocious puberty
9. Bone age interpretation: advanced in precocious puberty (risk of short adult stature), delayed in constitutional delay (good prognosis for final height)
10. Self-limited delayed puberty and congenital HH can look identical early on - longitudinal follow-up is often required to distinguish them

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• Medical Physiology (Boron & Boulpaep), pp. 1587-1590
• Ganong's Review of Medical Physiology 26th Ed., pp. 401-404
• Harrison's Principles of Internal Medicine 22E (2025), pp. 3152-3154
• Textbook of Family Medicine 9e, pp. 1038-1042
• Goldman-Cecil Medicine