AKT · Child health/Growth, GI & MSK

Precocious puberty

Secondary sexual development before age 8 (girls) / 9 (boys)

Overview

Onset of secondary sexual characteristics before 8 years in girls or 9 years in boys. Split into CENTRAL (gonadotropin-dependent — premature activation of the HPG axis, pubertal LH/FSH) and PERIPHERAL (gonadotropin-independent — sex steroids from a gonadal/adrenal/exogenous source, suppressed LH/FSH). Central is usually idiopathic in girls but more often pathological in boys (a CNS lesion).

Recognise

Girls: breast development → pubic hair → menarche, with a growth spurt and ADVANCED bone age
Boys: testicular/penile enlargement, pubic/axillary hair, deepening voice, acne — virilisation is far more likely to be PATHOLOGICAL than in girls
Central = consonant (normal-sequence) puberty with bilaterally enlarged testes; peripheral = out-of-sequence virilisation, often with small or asymmetrically enlarged testes

Red flags

Boy with rapid virilisation → exclude an androgen-secreting tumour and CAH
Neurological signs/headache → CNS lesion driving central PP (MRI brain)
Café-au-lait macules + bone pain/fracture → McCune–Albright syndrome

Differentials & how to tell them apart

Sex-cord-stromal (Leydig-cell) testicular tumourvirilising boy with a UNILATERALLY enlarged/irregular testis — androgen-secreting; the lesion behind isolated peripheral precocity in a boy

Congenital adrenal hyperplasiavirilisation from 21-hydroxylase deficiency; raised 17-OHP, small testes, possible salt-wasting history

McCune–Albright syndromeperipheral PP + café-au-lait (coast-of-Maine) macules + polyostotic fibrous dysplasia

Premature thelarche / adrenarcheISOLATED breast or pubic-hair development, no growth spurt, bone age NOT advanced — benign normal variants

Phaeochromocytomacatecholamine excess (paroxysmal hypertension, sweating, headache) — does NOT virilise; a distractor, not a cause of precocious puberty

Investigations

Bone age (advanced); basal + GnRH-stimulated LH/FSH to split central vs peripheral; testosterone/oestradiol; 17-OH-progesterone (CAH); DHEAS/adrenal androgens; MRI brain (central, especially in boys); testicular/pelvic/adrenal ultrasound (peripheral source).

Management

Confirm and localise (central vs peripheral), image accordingly; GnRH analogue for central PP, treat the cause for peripheral

1Establish whether puberty is central (pubertal LH/FSH, MRI brain) or peripheral (suppressed LH/FSH → seek a gonadal/adrenal source on ultrasound, 17-OHP, androgens).
2Central → GnRH analogue to halt progression and protect height; peripheral → treat the tumour/CAH/syndrome.

GnRH analogue (e.g. leuprorelin) — central PP — suppresses the axis to halt progression and preserve final adult height

Treat the underlying cause — resect an androgen-secreting tumour; glucocorticoid for CAH; aromatase inhibitor/antiandrogen in McCune–Albright

Key points

A virilising 8-year-old BOY (pubic/axillary hair, enlarged penis, deep voice) signals androgen excess — think androgen-secreting Leydig/sex-cord-stromal testicular tumour, CAH or an adrenal tumour, NOT phaeochromocytoma (catecholamines do not virilise). Bone age is advanced and final height is compromised by early epiphyseal fusion.

Monitor & prognosis

Growth velocity, bone age, pubertal staging; axis suppression on a GnRH analogue.

Good with treatment; untreated peripheral causes compromise final height and need the source removed.

Source: NICE CKS — Puberty; BSPED