192/194 puberty and growth

Question 1

What is puberty?

Answer 1

maturation of the hypothalamic-pituitary-gonadal axis

transition from sexually immature to potentially fertile

iwhere secondary sexs characteristics appear

Question 2

What is adrenarche?

Answer 2

maturation of the hypothalamic-pituitary-adrenal axis

Question 3

What is pubarche?

Answer 3

first appearance of pubic hair

Question 4

What is thelarche?

Answer 4

first appearance of breast tissue

Question 5

What is menarche?

Answer 5

first menstrual period

Question 6

Pulsatile release of _______ from the hypothalamus stimulates the release of _______ and ______ from the pituitary gland.

Answer 6

Pulsatile release of GnRH from the hypothalamus stimulates the release of LH and FSH from the pituitary gland.

Question 7

What is the “mini-puberty of infancy”?

Answer 7

a mini puberty where GnRH stimulates LH and FSH release shortly after birth until 6-12 months of age

Question 8

Which neuropeptides are the gatekeepers of puberty?

Answer 8

neurokinin B and kisspeptin

NKB activates kisspeptin

Question 9

What is the relationship between puberty and adrenarche?

Answer 9

they are separate processes, but generally occur around the same time (but adrenarche usually precedes puberty)

Question 10

Is pubic hair a sign of puberty?

Answer 10

no - it is a sign of pubarche (a subset of adrenarche, which is separate from puberty)

Question 11

What is Tanner stage 1?

Answer 11

prepubertal

Question 12

What is the timeline for early puberty in girls? Boys?

Answer 12

signs of thelarche in a girl prior to 7-8 years old

testicular enlargment in a boy prior to 9 years old

Question 13

What is the timeline for delayed puberty in girls? Boys?

Answer 13

lack of secondary sex characteristics by age 13 in girls and 15 in boys

Question 14

When is menarche considered early? Late?

Answer 14

early = before 9.5 years old

late = after 16 years old

Question 15

What is the cause of central precocious puberty?

Answer 15

gonadotropin release prior to age 7/8 in girls or 9 in boys

can be caused by intracranial lesions, neurofibromatosis, hydrocephalus

Question 16

What is the cause of peripheral percocious puberty?

Answer 16

gonadotropin independent precocious puberty where sex steroids are produced without gonadotropin stimulation

can be caused by ovarian cysts, McCune-Albright syndrome, testotoxicosis, familial causes, or gonadal/adrenal tumors

Question 17

What is McCune Albright syndome?

Answer 17

peripheral precocious puberty + cafe-au-lait spots + polyostotic fibrous dysplasia

Question 18

What is the cause of late puberty?

Answer 18

temporary hypogonadotropic hypogonadism due to lack of activation of the HPG axis

could also be primary hypogonadosim (hypergonadotropic hypogonadism)

Question 19

What are causes of hypogonadotropic hypogonadism?

Answer 19

constitutional delay of growth, inadqeuate energy (ex. anorexia), Kallmann syndrome, Kisspeptin mutation, interrupted puberty

Question 20

What is Kallmann syndrome?

Answer 20

a cause of hypogonadotropic hypogonadism associated with anosmia due to failure of olfactory placodes and GnRH neurons to migrate prenatally

Question 21

What are causes of primary gonadal failure/hypergonadotropic hypogonadism?

Answer 21

chromosomal abnormalities (klinefelter syndrome, turner syndrome)

trauma to both gonads

autoimmune destruction

Question 22

During which periods of childhood are LH, FSH, and sex steroids elevated?

Answer 22

fetal life, infancy, puberty

Question 23

GPR54 knockout mice have which of the following?

a) central precocious puberty
b) delayed puberty in females
c) gonadotropin independent precocious puberty
d) hypogonadotropic hypogonadism

Answer 23

d) hypogonadotropic hypogonadism

Question 24

A 7 yo boy presents with body odor and pubic hair for the last 6 months. Is this precocious puberty, premature pubarche, or premature adrenarche?

Answer 24

premature pubarche with other signs of adrenarche (but can’t say for sure without biochemical evidence)

Question 25

An 8 yo Caucasian girl presents with breast development, left greater than right, over the past year. Her mother had menarche at 15 and her father remembers pubertal timing being normal. Examination reveals left breast is Tanner 2 and right is Tanner 3. What would be your evaluation and next step? a) this is normal development; reassure parents b) asymmetric breast development is concerning for cancer; recommend ultrasound of breast tissue c) this is premature thelarche; evalutation should be done for precocious puberty

Answer 25

c) this is premature thelarche; evalutation should be done for precocious puberty

Question 26

What is the major endocrine regulator of growth during fetal life?

Answer 26

insulin ## Footnote *pituitary hormones do not have a significant impact on growth during fetal development*

Question 27

Which hormone that is important for growth during childhood is secreted in a pulsatile manner?

Answer 27

growth hormone

Question 28

What are the main effects of thyroid hormone during growth and development of infancy/childhood?

Answer 28

acts on epiphyseal cartilage, which promotes chondrocyte proliferation and ephiphyseal fusion

Question 29

What is the effect of growth hormone on bone?

Answer 29

increases osteoclast differentiation and activity, increases osteoblast activity, increases bone mass via endochondral bone formation

Question 30

What is the effect of growth hormone on muscle?

Answer 30

increased amino acid transport, increased nitrogen retention, increased lean mass, increased energy expenditure

Question 31

What is the effect of growth hormone on adipose tissue?

Answer 31

increased lipolysis, decreased lipogenesis

Question 32

When are IGF-1 levels at their highest levels?

Answer 32

during puberty

Question 33

Infants less than 2 years old are measured \_\_\_\_\_\_\_\_\_\_\_\_, children greater than 2 years old are measured \_\_\_\_\_\_\_\_\_\_\_.

Answer 33

Infants less than 2 years old are measured **laying down on a length board**, children greater than 2 years old are measured **standing with a stadiometer**.

Question 34

What are the clinical red flags for growth?

Answer 34

height \< 3rd percentile height significantly below genetic potential abnormally slow growth rate downwardly crossing percentile channels after 18 months to 2 years of age

Question 35

What is the difference in growth rate between primary and secondary growth disorders?

Answer 35

primary growth disorders: linear growth rate is normal initially but slows down when bones fuse OR growth can be along the growth curve and then stops sooner than a normal child secondary growth disorders:slow linear growth rates with delayed bone age

Question 36

What are the normal growth rates during infancy, childhood, adolescence?

Answer 36

0-12 months: 25 cm/yr 12-24 months: 12.5 cm/yr 2 years - onset of puberty: 6-8 cm/yr pubertal peak: 9-10 cm/yr

Question 37

Name causes of primary growth abnormalities?

Answer 37

osteochondrodysplasias, down syndrome, turner syndrome, russel silver syndrome

Question 38

What is the difference in growth curve between congenital and acquired GH hormone deficiency?

Answer 38

congenital = normal in the first few months of life, but then slows around 9-12 months of age; weight is maintained acquired = normal growth rate prior to deficiency, will cross down and then cease eventually