Epidemiology & Risk Factors

Definition: Development of secondary sexual characteristics in girls <8 yo or boys <9 yo.
Central PP (gonadotropin-dependent):
- Girls: >90% idiopathic.
- Boys: >90% secondary to CNS lesions (e.g., hypothalamic hamartoma, astrocytoma, trauma, cranial irradiation).
Peripheral PP (gonadotropin-independent):
- Caused by autonomous sex hormone secretion (gonads, adrenals, or exogenous exposure).
- Associated w/ McCune-Albright syndrome, CAH, Leydig cell tumors, granulosa cell tumors.

Clinical Features

Accelerated growth velocity & advanced skeletal maturation.
Girls: Thelarche (breast development), pubarche (pubic hair), menarche.
Boys: Testicular enlargement (testicular volume >4 mL or length >2.5 cm), phallic enlargement, pubarche, voice deepening, acne.
Signs of underlying pathology:
- Café-au-lait spots w/ irregular borders (McCune-Albright).
- Focal neurologic deficits, headaches, or signs of ↑ ICP (CNS tumor).
- Virilization/hirsutism in girls (CAH or adrenal tumor).

Initial: Bone age (BA) radiograph (left hand/wrist).
- If BA ≤ chronological age (CA): Likely normal variant (e.g., premature thelarche/adrenarche). c
- If BA > CA: Assess gonadotropins.
Key Labs: Basal LH level.
- If high: Central PP.
- If low: Perform GnRH stimulation test.
  - LH rises (pubertal response) -> Central PP.
  - LH remains low (prepubertal response) -> Peripheral PP.
Imaging & Further Workup:
- Central PP: Brain MRI w/ contrast (rule out hypothalamic hamartoma or CNS tumor).
- Peripheral PP:
  - Girls: Pelvic US (ovarian cysts, granulosa cell tumor).
  - Boys: Testicular US (Leydig cell tumor).
  - Both: Serum DHEA-S, 17-OHP, testosterone levels (evaluate for CAH or adrenal tumors).

Premature adrenarche: Isolated pubic/axillary hair + body odor; BA normal or slightly advanced; normal basal LH.
Premature thelarche: Isolated breast development; BA matches CA; normal basal LH.
McCune-Albright syndrome: Triad of peripheral PP, irregular café-au-lait spots (coast of Maine), and polyostotic fibrous dysplasia (recurrent bone fractures).
Congenital Adrenal Hyperplasia (CAH): Peripheral PP + virilization + electrolyte abnormalities (salt-wasting 21-hydroxylase deficiency); elevated 17-OHP.

Central PP:
- GnRH receptor agonists (e.g., depot leuprolide) continuous therapy to downregulate GnRH receptors, suppressing LH/FSH secretion.
- Prevents premature epiphyseal fusion and maximizes adult height.
Peripheral PP:
- Treat primary cause.
- Exogenous hormone exposure: Remove source.
- CAH: Glucocorticoids (hydrocortisone).
- Tumors (Leydig/granulosa cell): Surgical resection.
- McCune-Albright: Aromatase inhibitors (e.g., anastrozole) or SERMs (e.g., tamoxifen).

Premature epiphyseal plate fusion resulting in short adult stature.
Psychosocial distress, bullying, and early sexualization.
CNS mass complications (e.g., hydrocephalus, vision loss) if central tumor etiology.

Benign variants of puberty are self-limiting, non-progressive patterns of early sexual development.
Bone age is typically normal (equal to chronological age), and growth velocity is within normal limits.

Premature Thelarche (PT): Girls <2 yo.
Premature Adrenarche (PA): Girls <8 yo, boys <9 yo; RFs: Obesity, SGA history.
Constitutional Delay of Growth and Adolescence (CDGA): Boys > girls; FHx of “late bloomers.”

PT: Isolated breast development (bilateral or unilateral). No pubic/axillary hair.
PA: Isolated pubic/axillary hair, apocrine body odor, mild acne. Normal breast/testicular volume. c
CDGA: Delayed puberty (girls >13, boys >14), short stature, but normal growth velocity (parallel to growth curve).

Initial: Bone Age (BA) X-ray (rules out true precocious puberty).
- PT & PA: BA = Chronological age (normal).
- CDGA: BA < Chronological age (delayed, matches height age).
Labs: Prepubertal LH/FSH. Slightly elevated DHEAS for age in PA (normal 17-OHP).
Growth Velocity: Normal (differentiates from true precocious puberty).

Central Precocious Puberty: Diff by advanced BA, accelerated growth, and ↑ LH (basal or GnRH-stimulated).
Peripheral Precocious Puberty: Diff by advanced BA, accelerated growth, and low LH (suppressed by peripheral sex steroids).
Hypogonadotropic Hypogonadism: Diff from CDGA by lack of growth spurt, persistently low gonadotropins, or associated anosmia (Kallmann).

First-line (PT & PA): Reassurance and observation every 3-6 mos. c
First-line (CDGA): Reassurance & monitoring (reassure that normal final adult height is achieved).
Refractory/Psychosocial distress (CDGA in boys >14 yo): Short-course low-dose testosterone.

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