puberty Flashcards
Hypothalamic pituitary gonadal axis variations by age
Active in fetal development, functions in infancy and after infancy enters quiescent state (juvenile pause). FSH > LH in prepuberty. LH > FSH in puberty
gonadarche
Hypothalamic GnRH secretion stimulates gonadotropes to secrete FSH and LH causing gonadal maturation and production of sex steroids
adrenarch
maturation of the adrenal gland and production of the adrenal androgens, primarily DHEA-S and androstenedione. Causes pubic hair, axillary hair, body odor and acne in both boys and girls
Normal age of pubertal onset
Boys: 9-14 years. Girls: 8-13yrs (caucasian), but on avg 1 year earler for African American and Hispanic girls. Menarche usually occurs 1.5-2 years after pubertal onset
First physical signs of puberty
testicular enlargement >3 ml (or >2.2 cm) in boys (mediated by FSH and LH) and breast bud development in girls (mediated by estrogen)
timing of puberty in boys
Testes (11.8 yrs) > pubic hair (12 yrs) > penile enlargement (13 yrs) and peak height velocity (14 yrs)
What determines bone age advancement
estrogen in both boys and girls (testosteron is converted to estrogen by aromatase enzyme in boys). Onset of puberty correlates with bone age. Girls start puberty at bone age of 10.5-11yrs. Boys start puberty at bone age of 11.5-12 yrs
Define delayed puberty
Boys with delayed puberty have no testicular enlargement by age 14 years or no completion of genital growth after 5 yrs. Girls with delayed puberty have no breast development by age 13 years or no menses 4 years after pubertal onset or by age 16 years
Causes of delayed puberty
- hypothalamic-pituitary axis dysfunction: hypogonadotropic hypogonadism. 2. Gonadal dysfunction: hypergonadotropic hypogonadism (decreased negative feedback of sex steroids on brain causes elevated gonadotropins)
Most common cause of delayed puberty associated with low gonadotropins
Constitutional delay of growth and puberty. Children grow at normal prepubertal rate but are at shorter height percentile than expected. Bone age is delayed and onset of puberty is delayed, but puberty follows normal pattern of progression. Growth continues after peers stop gorwing and genetic height pontential is usually acheived. Family history of late bloomers
Types of hypogonadotropic hypogonadism
Reversible: FSH/LH levels suppressed during chronic illness, malnutrition, stress, anorexia, hyperprolactinemia and hypothyroid. Permanent: idiopathic, Kallmann syndrome (GnRH deficiency with anosmia aka lack of smell), congenital hypopituitarism, CNS defects, Prader-Willi, pituitary tumor, CNS infection, infiltrative dz, autoimmune hypophysitis
Causes of primary gonadal failure
Cogenital: Klinefelters (47, XXY), Turners (45, XO), gonadal dysgenesis, vanishing testes syndrome, and Noonan syndrome. Acquired: chemo, irradiation, galactosemia,testicular torsion, mumps orchitis and cryptorchidism
Klinefelters phenotype
microphallus, small testes, learning disabilities, eunochoid, delayed puberty, gynecomastia, infertility
Workup for delayed puberty
sense of smell, Bone age, gonadotropins, CBC, ESR, BMP, Thyroid, prolactin, testosterone/estradiol. Karyotype if hypergonadotropic
Treatment of delayed puberty
Testosterone replacement therapy in boys. Low dose estrogen followed by cyclic therapy of estrogen and progestin in girls
Define precocious puberty
boys: pubertal development before 9 years. Girls: development before 8 years (caucasian) or 7 years (african american and hispanic)
complete vs incomplete precocious puberty
Complete: early onset and progression of pubertal development with linear growth acceleration and bone age advancement. Early closure of growth plates possible. Incomplete: early onset but not progressive. This includes benign premature thelarche and benign premature adrenarche
Central vs peripheral precocious puberty
Central: Premature activation of hypothalamic-pituitary-gonadal axis. 5% of girls have CNS abnormality. 50% of boys have CNS abnormality. Peripheral: Puberty occurs independent of GnRH and gonadotropin stimulation.
Causes of central precocious puberty
CNS causes: hypothalamic hamartoma, suprasellar tumor, hydrocephalus, previous CNS infection, major head trauma, cranial irradiation
Causes of peripheral precocious puberty in boys
due to excess androgen production caused by congenital adrenal hyperplasia, adrenal tumor, Leydig cell tumor, hCG tumor, testotoxicosis (mutation of LH receptor causing it to be constitutively activated) or exogenous androgens
Causes of peripheral precocious puberty in girls
excess estrogens producd by ovarian cyst, ovarian granulosa cell tumor or exogenous estrogens. Also lavender products. Girls may present only with signs of androgen effects such as pubic hair, axillary hair, oily skin and/or acne
Causes of peripheral precocious puberty in both sexes
hypothyroidism (TSH is like FSH, breast development or testicular enlargement with delayed bone age and poor linear growth), McCune-Albright syndrome (triad of precocious puberty, café au lait spots and polyostotic fibrous dysplasia caused by activated mutation in G protein).
Precocious puberty Physical exam - testes
Bilaterally testicular enlargement may be due to central precocious puberty, activation of the LH receptor by a hCG producing tumor, testotoxicosis, or McCune-Albright Syndrome. Unilateral testicular enlargement is usually associated with a testicular tumor. prepubertal sized testes seen in adrenal disorder and exogenous androgen exposure
Precocious puberty labs
Central: LH and FSH may or may not be in pubertal range. GnRH stimulation test shows pubertal LH response to GnRH. Peripheral: LH and FSH levels are suppressed. GnRH stimulation test shows prepubertal LH response
precocious puberty additional tests
pelvic ultrasound, adrenal/testicular ultrasound, estradiol, androgens
Treatment of central precocious puberty
GnRH analogues- leuprolide acetate or histrelin down regulate pituitary GnRH receptors and decrease gonadotropin secretion
Treatment of peripheral precocious puberty
Surgery if tumor. Glucocorticoids for congenital adrenal hyperplasia. Watchful waiting for ovarian cysts. Aromatase inhibitor for girls with McCune-Albright syndrome. Boys with this syndrome are treated with ketoconazole or androgen blocker + aromatase inhibitor
Incomplete precocious puberty
Premature thelarche (onset of breast development, can occur under 2 years due to ovarian hormone production during infancy. Often regresses by 2 yrs.) and adrenarche (pubic hair/ axillary hair with normal height and bone age)- variants of normal development and do not require intervention.
Premature adrenarche differential
adrenal/ovarian tumors, late onset congenital adrenal hyperplasia
