Delayed Puberty/Precocious Flashcards
(95 cards)
infant with Y chromosome
expression of transcription factor SRY initiates cascade gene expression that directs formation of testes without SRY ovaries develop
Sexual differentiation is complete at
12 weeks
disorders of sexual development
arise from 3 main process; gonadal differentiation, steroidogensis, androgen action
DSD
often visible during newborn period; some arise during abnormal pubertal development
Gonadal Differentiation
testes/ovaries don’t develop-ambiguous genitalia or sex reversal
Deficiency of 21 hydroxylase
enzyme in cortisol and aldosterone- overproduction of adrenal androgens- most common form of congenital adrenal hyperplasia
Disorder of androgen action
androgen insensitivity syndrome (AIS) caused by inactivating mutation in androgen receptor gene- individuals have normal appearing female external genitalia with a short vagina, absent mullerian structures, absent wolffian structures, gonads located either intra abd or in inguinal canal, tx surgery for inguinal hernia reveals testis in hernia sack
Precocious puberty in girls- definded
pubertal development occurring below the age limit set for normal onset of puberty
Precocious puberty in girls- dx
if onset of sex characteristics occurs before 8 in caucasian girls, 7 years in AA and hispanics
Precocious puberty in girls- prevalence
more common in girls than boys, age of onset may be advanced by obesity
Precocious puberty in girls is either
Central or Peripheral
Central PP
activation of hypothalamic GnRH pulse generator, increase in gonadotropin secretin, and resultant increase in production in sex steroids; sequence of hormonal/ physical events is identical to normal puberty, generally idiopathic or secondary to CND abn that disrupts prepubertal restraint on GnRH pulse generator
Peripheral PP
LH response to GnRH stimulation is suppressed by feedback inhibition of the hypothalamic-pituitary axis
Girls with ovarian tumors/cysts
estradiol levels with be markedly elevated
Girls who present with pubic and/or axillary hair but no breast development
obtain androgen levels and 17 hydroxyprogesterone
Precocious puberty in girls- S&S
begins with breast development- pubic hair growth and menarche
accelerated growth and skeletal maturation- may temp be tall for age b/c skeletal maturation advances at more rapid rate than linear growth, final adult stature may be compromised
Precocious puberty in girls- Labs
estradiol level- draw to r/o ovarian tumor or cyst
if bone age is advanced- further lab tests are warranted
random FSH/LH may still be prepubertal range- stimulation of GnRH
Precocious puberty in girls- causes Central
Idiopathic, CNS abn- acquired, congenital, tumors
Precocious puberty in girls- causes Peripheral
congenital adrenal hyperplasia, adrenal tumors, McCune- Albright Syndrome, Familial male limited gonadotropin independent precocious puberty, gondal tumors, exogenous estrogen, ovarian cyst, HCG secreting tumors
Imaging- Precocious puberty in girls
xray of hand and wrist to determine skeletal maturity
Central PP- Imgaing
MRI of brain to evaluate for CNS lesions
IF labs suggest PP- Imaging
US of ovaries and/or adrenal gland
Central PP- Tx
tx with GnRH analogues that down-regulate pituitary GnRH receptors- decrease gonadotropin secretion- Leuprolide (IM once a month) histrelin (sub-dermal implant); projected final heights often increase as a result of slowing skeletal maturation- after stopping tx pubertal progression resumes- ovulation and pregnancy are possible
Peripheral PP-TX
dependent on underlying cause- cyst intervention normally not necessary, surgical resection and chemo indicated for rare adrenal ovarian tumor