203 Puberty and Adolescence Flashcards

0
Q

What is the term given for the the onset of breast development in girls?

A

Thelarche

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1
Q

What is the term given for the onset of increased androgen secretin by the adrenal cortex?

A

Adrenarche

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2
Q

What is the average age of onset of menarche in the UK?

A

13

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3
Q

Where do the gonads develop from in utero?

A

Somatic mesenchyme and primordial germ cells

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4
Q

Which week of development does gonadal development happen?

A

6

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5
Q

What does the presence of the Y chromosome lead to in development?

A

testicular development

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6
Q

Which gene on the Y chromosome leads to testicular development?

A

SRY

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7
Q

What happens in development in the absence of Y chromosome?

A

Ovarian development

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8
Q

What does completion of gonadal development require?

A

Number of X chromosomes

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9
Q

What (in utero) is required for development of male internal genitalia? (Epididymis, vas def, seminal vesicles)

A

Androgen and AMH

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10
Q

Which cells make androgens in utero?

A

Leydig

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11
Q

Which cells make AMH in utero?

A

Sertoli

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12
Q

What does the absence of androgens and AMH lead to in utero?

A

Female internal genital development

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13
Q

What is the mechanism for development of the fallopian tubes, uterus and upper vagina in utero?

A

Müllerian ducts not inhibited by AMH and therefore able to develop

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14
Q

Is ovarian activity needed for development of female internal genitalia in utero?

A

No

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15
Q

What does the presence of androgens lead to in the development of male external genitalia?

A

Fusion of the urethral folds and penile/scrotal formation

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16
Q

What does the absence of androgens lead to in the development of the female external genitalia?

A

Allows development of labia, clitoris and lower 1/3 of vagina

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17
Q

Which hormone begins secreting from the hypothalamus in a pulsatile fashion at puberty?

A

GnRH

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18
Q

When is GnRH actually produced?

A

During the foetal period

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19
Q

Which 2 hormones are stimulated by GnRH and where are they secreted from?

A

LH and FSH from the anterior pituitary

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20
Q

What is stimulated by GRH?

A

Pituitary to produce GH

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21
Q

Which hormone inhibits GH?

A

Somatostatin

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22
Q

What does GH stimulate in the liver?

A

Production of IGF-1

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23
Q

What is the role of IGF-1 in puberty?

A

Mediates the effect of GH through negative feedback. Inhibits further secretion of GH and GRF. Stimulates GnRH secretion therefore increasing gonadal activity

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24
Q

What is the role of granuloma cells in the ovaries?

A

Surround oocyte and produce ovarian growth factors and convert testosterone into oestrogen when stimulated by FSH

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25
Q

Where are the a interna cells found?

A

Outside basal membrane of the follicle and produce androgens

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26
Q

Where are theca externa cells found?

A

Outermost layer of ovarian follicular cells and are mainly supportive - produce collagen

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27
Q

What 2 things does FSH stimulate in the ovaries?

A

Follicular growth - particularly granulosa cells

Conversion of testoserone to oestrogen by granulosa cells

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28
Q

What 2 things does LH stimulate in the ovaries?

A

Theca cells to produce androgens.

Ovulation - rupture of follicle, release of ovum, maintenance of corpus luteum after ovulation

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29
Q

Where are germ cels located in the testes?

A

In seminiferous tubule epithelium - they develop into sperm

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30
Q

Where are Sertoli cells situated?

A

Seminiferous tubule epithelium - secrete GF and nutrients supporting sperm development

31
Q

Where are leydig cells situated?

A

Between the seminiferous tubules and secrete testosterone

32
Q

What does FSH stimulate in the testes?

A

Sertoli cells to produce GFs and proteins including Inhibin B

33
Q

What does LH stimulate in the testes?

A

Leydig cells to produce testosterone

34
Q

What is the role of testosterone and Inhibin B in the testes?

A

Part of the negative feedback loop - inhibits GnRH + LH + FSH by the hypothalamus and pituitary

35
Q

What does the tanner staging measure?

A

Stages of puberty

36
Q

What is included in the tanner staging of pubertal development?

A

Breast development/ testicular development

Pubic hair + axillary hair growth

37
Q

What is the first physical sign of puberty in girls?

A

Breast budding

38
Q

What tanner stage is breast budding?

A

Stage 2

39
Q

At which age range do secondary sexual characteristics develop in girls?

A

9-14 years

40
Q

When does peak growth occur in girls?

A

10-14 years

41
Q

What triggers menarche?

A

Beginning of cyclic release of LH

42
Q

At what age is there a peak of testosterone secretion by leydig cells in boys (before onset of puberty)?

A

2 months

44
Q

Which hormone do Sertoli cells continue to secrete until puberty?

A

AMH

45
Q

At what age do boys develop secondary sexual characteristics?

A

10-14

46
Q

Which hormone stimulates the development of secondary sexual characteristics in boys?

A

Dihydrotestosterone

47
Q

The cyclic release of which hormone stimulates the production of dihydrotestosterone in boys?

A

LH

48
Q

At what age range does peak growth occur in boys?

A

13-16 years

49
Q

What is average testicular volume during peak growth in boys?

A

~15ml

50
Q

What is precocious puberty?

A

Early sexual development with initial increase in stature but decreased stature in adulthood

51
Q

What is true central precocious puberty?

A

Normal puberty but occurring earlier than usual

52
Q

What is the difference between TCCP (true central precocious puberty) in boys as compared to girls?

A

In girls = relatively normal and no investigations are needed, whereas in boys it is very rare and should alway be investigated

53
Q

Name 3 causes of TCCP

A
  1. Cranial irradiation
  2. Tumour
  3. Neurological disorder
54
Q

What investigations should be carried out in precocious puberty in boys?

A

Hormone levels, head MRI

55
Q

Name 4 causes of precocious pseudopuberty (6 listed)

A
Adrenal/gonadal tumour
Neurofibromatosis Type 1
McCune Allbright syndrome
Congenital adrenal hyperplasia
Severe hypothyroidism
Iatrogenic
56
Q

What are the features of Neurofibromatosis type 1?

5 listed

A
>6 cafe-au-lait spots
Neurofibromas
Axillary freckles
Optic gliomas
Sphenoid dysplasia
57
Q

What can sphenoid dysplasia in neurofibromatosis type 1 cause?

A

Eye protrusion

58
Q

What sequelae can arise from neurofibromatosis type 1?

4 listed

A

Precocious pseudopuberty
Phaeochromocytoma
Pulmonary HTN
Renal artery stenosis

59
Q

What is the predominant feature in neurofibromatosis type 2?

A

Bilateral acoustic neuromas

60
Q

What is McCune Allbright syndrome?

A

Genetic mutation causing bone and endocrine disorders with early puberty

61
Q

What is polyostotic fibrous dysplasia?In which disease causing precocious pseudopuberty it occur?

A

Bone fractures and deformities due to fibrous bone tissue replacing normal bone - McCune Allbright syndrome

62
Q

What endocrine dysfunctions occur in McCune Allbright syndrome?

A

Hyperthyroidism

Cushing’s

63
Q

Which is the only cause of precocious pseudopuberty which may arrest growth?

A

Severe hypothyroidism

64
Q

What will hormone assays show in pseudo precocious puberty?

A

Decreased LH and FSH

Increased oestrogen and testosterone

65
Q

What is the management of precoious pseudopuberty?

3 things listed

A
  1. GnRH analogues - which cause continuous stimulation of the pituitary which therefore causes switch off of the HPG axis
  2. Sex steroid restriction/antagonisation Rx e.g. spironolactone - blocks androgen receptors
  3. Surgery to remove tumours
66
Q

What is classified by delayed puberty?

A

Absence of secondary sexual characteristics by:
boys 14
girls 13

67
Q

Name 3 central causes of delayed puberty (with intact HPG axis)

A

Chronic disease/ anorexia
Psychosocial deprivation
Steroids
Hypothyroidism

68
Q

What can affect the HPG axis to cause delayed puberty?

6 listed

A
  1. Tumours e.g. cranial/optic gliomas which can compress the hypothalamus/pituitary
  2. Congenital pituitary/hypothalamic defects
  3. Irradiation
  4. Trauma
  5. Kallmans syndrome
  6. Prader-Willi syndrome
69
Q

What is Kallman syndrome?

A

Isolated GnRH deficiency leading to hypogonadism.

Cause by a genetic hypothalamic abnormality

70
Q

What is Prader-WIlli syndrome?

A

Genetic condition similar to Downs with multisystem effects

71
Q

Name 4 gonadal causes of delayed puberty

7 listed

A
  1. Bilateral testicular damage
  2. PCOS
  3. Noonan’s syndrome (male turners)
  4. Turners
  5. Irradiation/chemo
  6. Intersex disorders - androgen insensitivity disorder
  7. Thalassaemia
72
Q

What is androgen insensitivity disorder?

A

Mutation causing inability to produce androgen receptor - causing delayed puberty

73
Q

How can thalassaemia cause delayed puberty?

A

May cause ischaemic damage to the gonads due to occlusion of the blood supply

74
Q

What are the characteristics of Turner’s syndrome?

7 listed

A
Ovarian dysgenesis
Webbed neck
Mental retardation
Short stature
Delayed puberty 
Amenorrhoea
Infertility
75
Q

What is the genetic mutation in Turner’s syndrome?

A

Part or all of one X chromosome missing