4.1 Puberty & HPG axis

Question 1

gonadarche

Answer 1

activation of gonads

Question 2

menarche

Answer 2

onset of menstruation at puberty

Question 3

hormone sec rated by pineal gland

Answer 3

melatonin

Question 4

male secondary sexual characteristics

Answer 4

-increased thicker hair on trunk, pubis, axillae, face
-larynx bigger
-deeper voice
-increased bone mass
-increased muscle mass and strength

Question 5

normal puberty age in girls

Answer 5

8-13

Question 6

female secondary sexual characteristics

Answer 6

-pubic and axillary hair
-labia minora and major enlarge
-keratinisation of vaginal mucosa
-uterine enlargement
-increased fat on hips/thighs

Question 7

fist sign of puberty
-boys
-girls

Answer 7

-testicular enlargement
-breast bud development

Question 8

when is HPG axis switched on?

Answer 8

puberty

Question 9

how long before physical changes of puberty do hormone changes start?

Answer 9

1 year

Question 10

first hormone changes

Answer 10

increased freq and amplitude of pulsatile GnRH, first at night then in day

Question 11

hormones associated with onset of puberty

Answer 11

FSH & LH steady rise

Question 12

after maturation of synaptic connections, what are the pulses of GnRH?

Answer 12

-males 2 hourly
-females changes according to menstrual cycle phases

Question 13

why is GnRH release pulsatile?

Answer 13

if continuous, it would desensitise FSH and LH receptors

Question 14

high levels of which hormones initiates gonadal development?

Answer 14

FSH and LH

Question 15

which hormones stimulate gonads to produce oestrogen and testosterone?

Answer 15

FSH and LH

Question 16

inhibin inhibits which hormone specifically?

Answer 16

FSH

Question 17

in females, why does inhibin from developed follicle need to inhibit FSH?

Answer 17

stop more than one follicle developing each month

Question 18

granulose cells convert androgens to what?

Answer 18

oestrogen

Question 19

what maintains corpus luteum after ovulation?

Answer 19

LH

Question 20

hormone surge required for ovulation

Answer 20

LH

Question 21

theca internal cells release what?

Answer 21

androgens

Question 22

precocious puberty

Answer 22

first signs of puberty before 8 in girls/ 9 in boys

Question 23

central precocious puberty

Answer 23

premature activation of HPG axis with elevated GnRH levels

Question 24

causes of central precocious puberty

Answer 24

-idiopathic, constitutional
-CNS lesions: infection, trauma, surgery
-obesity (reach 47kg sooner)

Question 25

treatment of central precocious puberty

Answer 25

GnRH agonists to overstimulate and desensitise anterior pituitary so doesn't release LH and FSH stop when 'normal' time for puberty

Question 26

peripheral precocious puberty

Answer 26

increased male/female hormones independent of HPG axis maturation, so without elevated GnRH levels

Question 27

causes of peripheral precocious puberty

Answer 27

-increased androgen production e.g. CAH -HCG secreting tumours e.g. granulose cell tumour, hepatoblastoma -primary hypothyroidism -obesity

Question 28

hormone levels in peripheral precocious puberty

Answer 28

-increased oestrogen/testosterone -decreased LH FSH

Question 29

can GnRH analogues be used for peripheral precocious puberty?

Answer 29

no response

Question 30

delayed puberty

Answer 30

no secondary sexual characteristics by 13 in girls, 14 in boys no period by 15

Question 31

causes of delayed puberty

Answer 31

-constitutional growth delay COMMON -malnutrition e.g. anorexia -IBD -hypothyroidism -hypogonadism e.g Turners, Klinefelters