Puberty and its abberrations Flashcards
What neurons acts as central processors for relaying signals from the periphery to GnRH neurons?
Kisspeptin neurons
What is pubarche?
presence of pubic hair
What is adrenarche?
presence of androgen dependent changes including pubic hair, apocrine body odor, acne, body hair
What is gonadarche?
earliest changes of gonads due to gonadotropin stimulation
What is thelarche?
presence of estrogen dependent breast tissue
What is menarche?
onset of menses
What is gynecomastia?
enlargement of male breast tissue resultant of imbalance of hormones
How is puberty defined in females?
presence of pubarche with thelarche
How is puberty defined in males?
presence of pubarche with gonadarche
What age defines precocious puberty in boys?
Before 9 years of age
What age is normal pubertal onset for boys and girls?
1) girls: 8-13
2) boys: 9-14
What hormones signify gonadarche?
1) in boys - testosterone
2) in girls - estrogen
What hormones signify adrenarche?
adrenal androgens (testosterone, DHEAS, androstenedione)
What hormone influences growth plate fusion?
estrogen in both sexes
What non-invasive test can be used to further define pubertal advancement?
bone age
What are the risks for precocious puberty?
1) early maternal menarche
2) low birth weight
3) excessive weight gain or obesity in infancy
4) after international adoption
5) after intercranial radiation
Is isolated FSH elevation idicative of precocious puberty?
No - FSH spikes with GnRH occur even in prepuberty states
What findings will you have gonadotropin-dependent puberty? (true puberty)
1) secondary sexual characteristics
2) bone age advancement
3) accelerated linear growth
4) gonadal maturation
5) gonadotropins (LH/FSH) - pubertal baseline and stimulated
6) sex steroids - pubertal
What findings will you have in gonadotropin independent puberty? (pseudoprecocity)
1) secondary sexual characteristics
2) bone age advancement
3) accelerated linear growth
4) None/minimal gonadal maturation
5) prepubertal gonadotropins (LH/FSH)
6) sex steroids - pubertal
What are some symptoms of McCune Albright Syndrome?
precocious puberty, cafe au lait pigmentation (coast of maine), polyostotic fibrous dysplasia
What mutation is found in McCune Albright syndrome?
activating mutation of the GNAS1 gene which encodes the alpha subunit of the G protein
What is testitoxicosis?
familial or sporadic male-limited sexual precocity
What mutation is found in testitoxicosis?
constitutive activation of mutant LH receptors (autosomal dominant or sporadic)
What are the signs/symptoms of testitoxicosis?
precocious puberty early in childhood (often by 2-3 years of age) , high testosterone, suppressed gonadotropins (testicular volume is less than expected for degree of sexual development)
What mutation is found in Albright’s hereditary osteodystrophy?
GNAS activating mutation that encodes for a Galpha subunit
How does temperature affect the mutation in albright’s?
1) at lower temperature (in gonads) gain of function - gonadotropin independent precocious puberty
2) at normal body temperature - loss of function (pseudohypoparathyroidism)
What is hCG?
human chorionic gonadotropin - an LH receptor agonist (high levels stimulate LH receptor thereby promoting androgen production)
What does hCG mediated sexual precocity rarely occur in girls?
both LH and FSH are needed for ovarian stimulation
What is the only form of sexual precocity with growth arrest?
Van Wyk-Grumbach Syndrome
What is Van Wyk-Grumbach syndrome?
sexual precocity in association with hypothroidism (often associated with galactorrhea, multiple ovarian cysts, little/no pubarche)
What can testosterone exposure cause?
isolated pubarche
What can estrogen exposure cause?
1) isolated thelarche in boys and girls
2) menstrual bleeding in girls
What defines delayed puberty?
lack of secondary sexual findings in boys by age 14 and age 12 or 13 in girls (lack of menarche by age 15-16 in girls)
What describes constitutional delay of growth and puberty?
1) short stature AND delayed puberty
2) see fall in growth % over first two years of life followed by normal pre-pubertal growth velocity and then delayed puberty
What is the differential for someone with normal growth, slight bone age delay and poor weight?
1) eating disorder
2) nutritional problem
3) competitive athlete
What is the differential for someone with normal growth, slight bone age delay and normal weight?
1) if LH/FSH is high - hypergonadotropic hypogonadism
2) prepubertal LH/FSH levels - if prolactin is normal (hypogonadotropic hypogonadism), if prolactin is elevated (prolactinoma or CNS mass)
What is the DD for decreased growth velocity, fairly normal bone age and elevated weight?
1) if prepubertal LH/FSH with normal thyroid function - cushing’s
2) prepubertal LH/FSH with elevated TSH - hypothyroidism
What is the DD for decreased growth velocity, fairly normal bone age and normal weight?
1) elevated LH/FSH and normal IGF-1 - Turners
2) prepubertal LH/FSH, low IGF-1
a) normal T4 and prolactin = isolated GH
deficiency
b) low T4, variable prolactin = consider
hypopituitarism
What is Kallman syndrome?
X-linked recessive form of hypogonadotropin hypogonadism associated with anosmia due to failed migration of GnRH neurons from the olfactory placode into the forebrain
What mutations are found in Kallman syndrome?
mutations in the KAL gene of Xp22.3
What is klinefelter syndrome?
the most common cause of male hypogonadism and infertility
What is the clinical course of klinefelters?
1) enter puberty normally but testosterone levels fall in late adolescence and early adulthood
2) some academic delays
3) long extremities
4) gynecomastia
When should you consider Turner Syndrome in your DD?
with short stature and ovarian dysfunction
What is the clinical course of Turners?
1) normal statural growth for 1st 2-3 years followed by deceleration and typically normal bone age
2) 1/3 enter puberty normally
