Disorders of Puberty Flashcards
In someone with hypogonadotrophic hypogonadism, the penis is _____________.
completely normal because the maternal hCG stimulates testosterone growth in the baby in the first trimester; however, the second and third trimesters require testosterone from the son, so cryptorchidism would result
Puberty requires a normal ____________ axis.
hypothalamic-pituitary
Babies usually have a “mini-puberty” at _________ of age.
two months - eighteen
Note: kids have pubertal levels of LH and FSH at this time.
LH and FSH will be __________ in girls with Turner syndrome.
extremely high
________________ is referred to as gonadarche.
The reactivation of GnRH secretion from the hypothalamus (usually occurring first at night then during the day)
_________________ are thought to stimulate GnRH secretion.
KISS-1 neurons
What relationship do LH and FSH have before and during puberty?
Prepuberty: FSH is greater than LH
Puberty: LH is greater than FSH
Laboratory evaluation of early puberty is unreliable because __________________.
GnRH secretion is pulsatile and usually occurs predominately at night in early puberty
Leuprolide is _______________.
an analog of GnRH
What is the most sensitive test for evaluating puberty in adolescents?
Give leuprolide and then measure LH and FSH. The gonadotrophic cells are more sensitive during puberty, so there will be a stronger response if a child has entered puberty. Also, LH will be higher.
What are the first signs of puberty in boys and in girls?
Boys: enlargement of the testes
Girls: breast buds
Why do boys become taller in puberty?
Because puberty is longer in boys
What hormone advances bone age?
Estrogen
In fact, this was discovered because a very tall man presented to doctors. He was in his twenties, but because he had a defect in his estrogen receptor, his bone plates had still not fused!
The ______________ cause development of pubic hair, axillary hair, and body odor.
adrenarche
What is the mean age of initiation of puberty in girls?
It varies by race/ethnicity: 9.5 for AA girls and 10.5 for caucasian girls.
Menarche usually occurs at _____________.
twelve years for girls of all races/ethnicities
What does Tanner staging comprise in girls and boys?
Girls: pubic hair and breast development
Boys: pubic hair and testicle size
What defines “delayed puberty”?
No puberty signs in boys at 14 or girls at 13
or
No menarche fours years after puberty starts in girls or completion of genital growth in males five years after puberty.
In terms of bone age, when do boys and girls typically start puberty?
Girls: 10.5 - 11
Boys: 11.5 - 12
What is the difference between central and primary/peripheral hypogonadism?
Central: pituitary is not making LH or FSH
Primary/peripheral: tissues are not responding to LH or FSH
How can you distinguish between constitutional growth delay and hypogonadotropic hypogonadism?
Four things:
1) . Bone age! Those with CGD will have younger bone ages, while those with HGHG will have bone ages similar to their actual ages.
2) . Adrenarche progresses independently of gonadotrophin (by an unknown mechanism), so boys with adrenarche in the absence of gonadarche is worrisome for HGHG. Absence of gonadarche with absence of adrenarche is less worrisome (i.e., it is more consistent with CGD).
3) . Those with CGD are generally thin, so a heavy child without gonadarche is worrisome.
4) . Disproportionately large arm span is characteristic of late/absence puberty.
What is Kallman syndrome?
Absence of GnRH with accompanying anosmia
This occurs because the GnRH neurons and the olfactory neurons originate and travel from the same embryonic tissue.
LH and FSH will rise only with ________________.
the disinhibition of GnRH
What are some causes of primary ovarian failure?
Turner syndrome (most common) Gonadal dysgenesis Radiation Galactosemia Chemotherapy Autoimmune (rare)
Note: all of these will produce hypergonadotropic hypogonadism (aka primary hypogonadism)
What are some causes of primary testicular failure?
Klinefelter's Cryptorchidism Testicular regression Radiation (more susceptible to radiation than the ovaries) Chemotherapy
Note: all of these will produce hypergonadotropic hypogonadism (aka primary hypogonadism)
Endocrinologists make a distinction between complete and incomplete precocious puberty. What is the difference?
Complete is early onset and early progression
Precocious puberty is defined as ___________________.
any signs of puberty before age 9 in boys, 8 in caucasian females, and 7 in AA females
“Puberty signs before the lower limit ages.”
Precocious puberty is more common in __________, but _____________.
girls; in boys, CNS issues are more common
One of the most common CNS causes of hypogonadism is _____________.
hypothalamic hamartoma
What is McCune-Albright syndrome?
A somatic mutation in the alpha subunit of GPCR that leads to constant activation; it is fatal if it occurs in all cells
Presenting signs are precocious puberty and café-au-lait spots that follow a dermatome.
What are the three main causes of precocious puberty in girls?
Ovarian cyst
Ovarian tumor
McCune-Albright
Explain the signs of adrenal-tumor-related precocious puberty.
Lots of virilization (due to the secreted androgens), but small testes due to low LH and FSH
Explain familial testotoxicosis.
LH-receptor mutations that lead to it being constitutively active produce excess testosterone which leads to increased testicular size.
Dark areolae are indicative of _______________.
elevated estrogen (often from cysts)
The most common cause of hypogonadotropic hypogonadism is _____________.
constitutional growth delay
How is hypogonadotropic hypogonadism treated?
Boys: testosterone replacement
Girls: initial estrogen replacement alone followed by estrogen and progestin replacement
What are the most common causes of gonadotroph-independent precocious puberty in boys?
CAH Familial testotoxicosis Leydig cell tumor hCG-secreting tumor Exogenous androgens (for example, if grandpa has a testosterone patch and hugs his grandson frequently)
How can you distinguish between central and peripheral precocious puberty using GnRH?
Those with peripheral precocious puberty will have prepubertal LH response, while those with central precocious puberty will have a pubertal LH response.
Where, in the HPG axis, do estradiol and testosterone accomplish negative feedback?
At the hypothalamus and pituitary
What physical changes occur in girls and boys at puberty?
Girls:
- Breast development
- Genital growth
- Maturation of vaginal mucosa
- Uterine growth
- Redistribution of fat
- Menarche
Boys:
- Enlargement of testes (by LH and FSH; the rest are by testosterone)
- Scrotal changes
- Sexual hair
- Deepening of voice
- Penile growth
- Increase in muscle mass
Testosterone replacement for boys and estrogen replacement for girls can be offered to treat ____________, though often only reassurance is needed.
constitutional growth delay
What disorder presents with hyalinization and fibrosis of the seminiferous tubules?
Klinefelter’s
What CNS disorders can cause central precocious puberty?
Anything that damages the sellar area:
- radiation
- infection
- hydrocephalus
- neoplasms
Those with precocious puberty are likely to have ___________ bone age.
advanced
How do you treat precocious puberty from congenital adrenal hyperplasia?
Give glucocorticoids. Returning the glucocorticoids (and mineralocorticoids, if necessary) back to normal silences the excess ACTH from the pituitary and thus limits the production of androgens.
