Chapter 38: Puberty Flashcards
What hormone starts puberty?
GnRH kicks in to start puberty, controlling production of sex hormones from the ovaries with higher changes causing the changes we see in puberty. adrenarche occurs, where the adrenals start producing dehydroepiandosterone that can be converted into more potent androgens (testosterone and dihydrotestosterone).
How long does sexual maturation take?
Sexual maturation takes 4 years. We see growth acceleration and breast development (thelarche), pubic hair development (pubarche), maximum growth rate (menarche) and ovulation. We typically view beginning for women as breast budding and pubic hair growth as height can be difficult to assess.
What is precocious puberty?
Precocious puberty: Secondary sex characteristics before 6 in African American girls and 7 in white girls.
3 causes of GnRH dependent precocious puberty
i) GnRH dependent: Due to early activation of the hypothalamic-pituitary-gonadal axis, usually
idiopathic (Hypothalamic hamartoma, craniopharyngiomata, gliomata, arachnoid or supreasellar cysts, CNS tumors).
Infectious causes (Encephalitic, meningitis, granulomata).
CNS Injury (Irradiation, Trauma, Hydrocephalus).
What is a sign in adults that would indicate a possible history of precocious puberty?
Early activation leads to early estrogen, which means closing of epiphyseal plates and shorter stature in females when older.
Causes of GnRH independent precocious puberty:
Causes:
- Exogenous sex steroid administration
- primary hypothyroidism
- ovarian tumors (Granulosa-Thecal cell, lipoid cell, gonadoblastoma, cystadenoma, germ cell)
- simple ovarian cyst
- McCune-Albright Syndrome
- premature thelarche/Adrenarche.
What is McCune Albright and how does it present?
McCune-Albright:
- Polyostotic fibrous dysplasia - Multiple bone fractures, cafe-aulait spots and precocious puberty. Premature menarche can be the first sign of the syndrome.
Defect in cellular regulation 2/2 mutation in a-subunit of the G-protein that stimulates ATP formation. Mutation causes ovary to make estrogen without
input from FSH.
Most common congenital adrenal hyperplasia result
Congenital adrenal hyperplasia: Most common is 21-hydroxylase deficiency which presents at birth with ambiguous genitalia (elevated 17hydroxyprogesterone levels)
What do we do with precocious puberty folks?
Main goals are to arrest and diminish sexual maturation until a normal pubertal age as well as to minimize adult height. Administer GnRH agonist
How do we define delayed puberty?
Defined as delayed when secondary sex characteristics have not appeared by the age of 13 years, there is no evidence of menarche by age 15 to 16 years or when menses have not begun 5 years after the onset of thelarche.
Hypergonadotropic hypogonadism is often causd by this chromosome mutation and presents with this lab finding
Most common cause of delayed puberty with an elevated FSH is gonadal dysgenesis or Turner Syndrome.
One X chromosome gone.
Presentation of Tuner syndrome
Pts have streak gonads with an absence of ovarian follicles, therefore gonadal sex hormone never occurs at puberty. Pt presents with webbed neck, short stature, primary amenorrhea, shield chest with wide spaced nipples, high arched palate.
Treating turner’s
Estrogen administration should be initiated at the normal time of initiation of puberty, and growth hormone should be initiated very early and aggressively to normalize height.
Something to be careful of with estrogen administration
Be careful with your abruptness of the estrogen as too much at the beginning could cause closure of the epiphyseal plates, while a delay can lead to osteoporosis in the teenage years.
What happens with hypogonadic hypogonadism?
The arcuate nucleus of the hypothalamus secretes GnRH in cyclic bursts which stimulates gonadotropins from the anterior pituitary to be released. Disrupting this causes FSH/LH to not be secreted and the ovaries don’t release estrogen
20% of the time this is just constitutional delay
