183Disorders Adrenarche Pubarche Gonadarche
Turner’s syndrome + − −
Congenital adrenal hyperplasia
(21α-hydroxylase)+ + −Kallmann syndrome + Absent in girls
Present in boys−Constitutional delay in growth and
puberty− − −- What is isolated premature pubarche?
Isolated premature pubarche is characterized by early appearance of pubic/axil-
lary hair without other secondary sexual characteristics and is preceded by pre-
mature adrenarche. Growth velocity and bone age are usually appropriate or
modestly increased for chronological age; however, the final adult height is
within the target range. Serum adrenal androgens level are mildly elevated and
LH response to GnRH is prepubertal. Children with small-for-gestational age
are at risk for childhood obesity and later may manifest as premature pubarche.
The exact mechanism remains elusive; however, increased secretion of adrenal
androgens due to increased 17, 20 lyase activity in zona reticularis or increased
sensitivity to circulating androgens has been proposed as the cause for isolated
premature pubarche.- What are the causes of premature pubarche?
Besides isolated premature pubarche, a normal variant, the other causes of pre-
mature pubarche include late-onset congenital adrenal hyperplasia (e.g.
21 α-hydroxylase deficiency), virilizing ovarian/adrenal neoplasms, glucocorti-
coid resistance syndrome, and exogenous androgen exposure.- A 5-year-old girl presented with appearance of pubic hair. On examination, she
was obese, had no breast development, and no signs of virilization. What is the
likely diagnosis?
The probable diagnosis in the index patient is premature pubarche due to obe-
sity-related premature adrenarche. The pointers to the diagnosis are isolated
appearance of pubic hair without any other secondary sexual characteristics,
normal height velocity, and appropriate bone age. Premature pubarche in obese
children is due to hyperinsulinemia and increased serum free IGF1 (due to
insulin- mediated decreased IGFBP1) leading to increased adrenal androgen
synthesis, and hence premature adrenarche. - Should all patients with premature pubarche undergo biochemical evaluation?
Assessment of bone age helps in predicting the need for biochemical evaluation
in a child with premature pubarche. If the child has premature pubarche without
any other signs of androgenization and bone age is not significantly advanced
(i.e., bone age >2.5 SD for chronological age), the child possibly has premature6 Precocious Puberty