Puberty

Question 1

HPG axis is active when?

Answer 1

In fetal development

Continues to fxn in infancy “mini puberty”

(after infancy, axis enters quiescent state, referred to as juvenile pause)

Question 2

What is HPG axis?

Answer 2

g

Question 3

After infancy, HPG axis enters quiescent state, referred to as ________

Answer 3

juvenile pause

Question 4

Gonadarche

Answer 4

pubertal onset started by RE-EMERGENCE of Hypothalamic GnRH secretion –>
Stim gonadotropins to secrete LH + FSH –>
bind receptors in ovaries/testes –>
gonadal maturation and the production of sex steroids.

Question 5

Prepuberty vs puberty lvls of FSH

Answer 5

Prepuberty: FSH > LH

Puberty:
LH>FSH

• early puberty may not be very helpful
• pulses and peaks are happening at night, so measuring lvls during day may be no good

Question 6

Lab evidence of puberty?

Answer 6

Serum sample of LH/FSH (during night)

or

Look at response of LH to a GnRH analog
- LH lvls >5-6 with pubertal response

Question 7

Estrogen stimulated changes in girls (6)

Answer 7

1. Breast development
2. Genital growth (labia minora)
3. Maturation of vaginal mucosa
4. Uterine/endometrial growth
5. Body compo changes (fat distribution more in hip)
6. Menarche (E + prog)

Question 8

Physical changes of Gonadarche in boys

Answer 8

1. Enlargement of testes #1 way to tell
   - mediated by gonadotropins (FSH + LH)
   _________
   everything else is caused by androgens (T or DHEA-S, androstenedione)
2. Scrotal changes
3. Sexual hair
4. Penile growth
5. Prostatic/seminal vesicle growth
6. Deepening of voice
7. Increase in muscle mass

Question 9

In both boys and girls, gonarche induces linear growth acceleration and bone age advancement. What is Bone age advancement mediated by?

Answer 9

Estrogen in both boys and girls

T is converted to E by aromatase in boys

Question 10

What causes pubarche in both boys and girls?

Answer 10

Pubarche: pysical signs of pubic hair, axillary hair, body odor, and acne.

Increased production of adrenal androgens (DHEA-S, androstenedione)

Question 11

Timing of puberty in girls

• Attainment of Tanner 2 breast development
• Menarche

Answer 11

Attainment of Tanner 2 breast development
- mean: 10.4

Menarche:
- mean 12.5 yrs

Question 12

Timing of puberty in boys
Testes > 3 ml
Pubic hair
Penile enlargement
Peak heigh velocity

Answer 12

Testes > 3 ml: 11.8 (9-14) yrs
Pubic hair: 12
Penile enlargement: 13
Peak heigh velocity: 14

Question 13

Delayed puberty in boys and girls

Answer 13

no puberty signs by Boys: 14 yrs
Girls: 13 yrs

or lack of progression
Girls: No menarche by 4 yrs after puberty starts
Boys: No completion of genital growth after 5 yrs

Question 14

Bone age is really physiologic age

Answer 14

Onset of puberty is commensurate with child's biologic age (bone age)
Boys start puberty at bone age of:
11.5-12 yrs
Girls start puberty at bone age of:
10.5-11 yrs

Question 15

Delayed puberty is due to?

Answer 15

Low gonadotropins
- HYPOgonadotropic (central) hypogonadism

Elevated gonadotropins
- HYPERgonadotropic (primary) hypogonadism

Question 16

Constitutional growth delay

Answer 16

late bloomers

Grows nl --> 
falls to lower % --> grows at that percentage -->
Puberty --> 
jumps back up to original % -->
Reaches full growth potential

Question 17

How to diff betwn late bloomer and indiv w/ hypogonadotropic hypogonadism?

Answer 17

1. Bone age
   ie: boy whos 15, and bone age is 13, and no pubertal signs: HH
2. Adrenarchy
   ie: absence of adrenarchy: late bloomer
   ie: adrenarche
   15 y/o w. bone age of 15, small testes: HH
3. Body habitus
   ie: late bloomers are typically thin

Question 18

Congenital causes of HYPOgonadotropic hypogonadism

Answer 18

1. Part of multiple hormone deficiencies: septo-optic dysplasia
2. Genetic syndrome: Prader willi syndrome

Question 19

Idiopathic hypogonadotropic hypogonadism (IHH)

Answer 19

isolated defect in GnRH or gonadotropins in the absence of any structural abnormalities of the hypothalamus or pituitary

Question 20

Kallman syndrome(579)

• Causes
• Presentation

Answer 20

1. Failure of complete puberty
   - a form of hypogonadotropic hypogonadism
2. Defective migration of GnRH cells
3. Defective formation of olfactory bulbs

Presentation:

• Low lvls of: GnRH, FSH, LH, T
• Infertility
• Ammenorrhea

Question 21

Acquired causes of Hypogonadotropic hypogonadism

Answer 21

1. Pituitary or hypothalamic tumor
2. Cranial irradiation
3. CNS infxn
4. Infiltrative diseases
   - histiocytosis, granulomatous disease, hemachromatosis
5. Autoimmune hypophysitis