Precocious puberty — formative SAQs

SAQ 1 — A 6-year-old girl with breast development and a growth spurt (20 marks, 30 minutes)

Stem. A 6-year-old girl is referred because her mother has noticed breast budding over six months, a smell of body odour, and that she is now the tallest in her class. On examination she has Tanner stage B3, P2, a height velocity of 9 cm per year, and a bone age advanced by two and a half years. Outline your assessment, the central-against-peripheral distinction and its investigation, and your management plan. [1]

Definition and the central-against-peripheral split. Precocious puberty is the onset of secondary sexual characteristics before 8 years in girls and before 9 years in boys. The first decision is mechanistic: central (GnRH-dependent, the axis switched on early) versus peripheral (GnRH-independent, a sex-steroid source bypassing the axis). Her consonant sequence — thelarche then adrenarche with a growth spurt — and her bone-age advance point toward a central, gonadotropin-driven process. [1] [2]

Assessment. Plot height, weight and body mass index with the mid-parental target height; confirm the growth velocity over four to six months; stage the breasts and pubic hair separately with Tanner; examine for red flags of an organic driver — neurological signs and visual fields, cafe-au-lait macules and bony deformity, an abdominal mass, and an exposure history (creams, essential oils, supplements). [1]

Investigation. A bone age (left hand and wrist) quantifies the biological cost; a baseline endocrine panel (luteinising hormone, follicle-stimulating hormone, oestradiol, dehydroepiandrosterone sulphate, androstenedione, 17-hydroxyprogesterone, thyroid function) begins the central-against-peripheral split; a GnRH stimulation test confirms central disease through a pubertal luteinising-hormone peak; a pelvic ultrasound assesses uterine and ovarian morphology. Because she is under 6 years, a brain and pituitary MRI is indicated to seek a hypothalamic hamartoma or tumour. [1] [2] [3]

Management. If central disease is progressive with height compromise, treat with a GnRH analog (leuprolide depot monthly or three-monthly, goserelin, or a histrelin implant) to suppress gonadotropins, halt bone-age acceleration and preserve adult height; monitor growth velocity and bone age every three to six months; continue until the bone age reaches the point where further height gain is negligible. Provide psychological support and a written shared-care plan. [3] [1]

SAQ 2 — A 4-year-old boy with a virilised body and small testes (20 marks, 30 minutes)

Stem. A 4-year-old boy has rapid linear growth, a deepening voice, severe acne, and pubic hair, but both testes measure 2 mL. His luteinising hormone and follicle-stimulating hormone are suppressed, his testosterone is high, and his 17-hydroxyprogesterone is normal. Discuss the differential, the significance of the testicular size, and the management principles. [1] [9]

Model answer. The small testes despite virilisation are the key sign: the testis cannot grow without gonadotropins, so a peripheral androgen source is driving the picture (GnRH-independent). The suppressed gonadotropins with high testosterone confirm this, and the normal 17-hydroxyprogesterone excludes congenital adrenal hyperplasia. The differential of a peripheral androgen source with normal 17-hydroxyprogesterone includes an adrenal or gonadal androgen-secreting tumour, familial male-limited precocious puberty (testotoxicosis, an activating LHCGR mutation — though that typically enlarges the testes), and a chorionic gonadotropin-secreting tumour. Adrenal and testicular imaging is indicated. [1] [9]

The management principle is that a GnRH analog cannot work, because the axis is already suppressed — treatment must be directed at the source. A tumour is managed surgically; testotoxicosis is managed with a combination of an antiandrogen (spironolactone or bicalutamide) and an aromatase inhibitor to protect the bone age. Throughout, the goal is to halt the sex-steroid exposure that is accelerating bone maturation and eroding adult height, and to support the child and family through a highly visible condition. [1] [3]