Hormones And Puberty

Question 1

Name the steps of puberty in order:

Answer 1

Adrenarche –> gonadarche –> thelarche –> pubarche –> menarche

Question 2

What and when is adrenarche?

Answer 2

The regeneration of the zona reticulus (in the adrenal glands) that produces androgens - 6 years old

Question 3

What and when is thelarche and what hormone is involved?

Answer 3

Breast development - estrogen - 8-11 years old

Question 4

What and when is pubarche and what hormone is involved?

Answer 4

Pubic and auxillary hair growth - androgens - 12 years old

Question 5

What and when is menarche and what hormone is involved?

Answer 5

The first period - estrogen - 13 years old

Question 6

What and when is gonadarche and what hormones are involved?

Answer 6

The onset of gonad hormone production - it starts with GnRH pulses that lead to FSH and LH pulses, both of which stimulate hormone production in the ovaries - 8 - 9 years old

Question 7

When does the growth spurt usually take place?

Answer 7

Between thelarche and pubarche

Question 8

What is the HPO axis?

Answer 8

Hypothalamic-pituitary-ovarian axis

Question 9

What does the zona reticulus do?

Answer 9

It is the site of the biosynthesis of androgen pre-cursors - androstenedione and DHEA

Question 10

Describe HPO activation from conception to puberty

Answer 10

1. Develops in the 1st trimester
2. Suppressed in utero
3. Mini puberty at birth
4. It reaches maximum levels at 1-1.5 years and the is supressed again.
5. Reactivated (cause unknown) during puberty, starting with GnRH pulses at night.
6. Levels out to pulses during the day.

Question 11

How is menarche different to a normal period?

Answer 11

It’s the first menstrual bleed but it doesn’t develop from the normal menstrual cycle - the sporadic nature of the HPO axis means that the estrogen levels are inconsistent. The estrogen, when present, leads to the proliferation of the endometrium and when estrogen drops at random, the lining sheds - menarche.

Question 12

Factors affecting age of puberty

Answer 12

1. Geographic location
2. Diet
3. Family history
4. Exposure to light

Question 13

BMI reference

Answer 13

Wang et al., 2016 - higher BMI = earlier menarche

Question 14

Exposure to light reference

Answer 14

Skandhan et al., 2018 - less light = earlier menarche

Question 15

Diet reference

Answer 15

Lee et al., 2016 - diet and endocrine disruptors = earlier menarche

Question 16

Family history reference

Answer 16

Tayeb et al., 2016 - age of mother and sister = age of menarche