SM_192b: Puberty Flashcards

1
Q

Puberty is ___

A

Puberty is maturation of the hypothalamic-pituitary-gonadal axis

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2
Q

Describe biochemical changes of puberty

A

Biochemical changes of puberty

  • Increase in pulsatile GnRH secretion (hypothalamus): increased frequency and amplitude, initially at night
  • Increase in pulsatile LH and FSH (pituitary): increased frequency and amplitude, initially at night, diurnal rhythm lost as puberty progresses
  • Increase in estradiol or testosterone (gonad: gonadarche)
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3
Q

Describe puberty over the lifespan

A

Puberty over lifespan

  • Pubertal hormones: high in fetus, low in infant, especially low in child, then increases to high in adult
  • CNS inhibition of GnRH pulse generator: low in fetus, higher in infant, highest in child, then decreases
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4
Q

Regulation of pubertal onset involves ____ and ____

A

Regulation of pubertal onset involves reactivation and stimulation / release of inhibition

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5
Q

Regulation of onset of puberty involves excitatory and inhibitory effects on ____ secretion

A

Regulation of onset of puberty involves excitatory and inhibitory effects on GnRH secretion

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6
Q

____ and ____ are the gatekeepers of puberty

A

Kisspeptin and neurokinin B are the gatekeepers of puberty

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7
Q

Kisspeptin levels ___ at pubertal onset

A

Kisspeptin levels increase at pubertal onset

  • Administration of kisspeptin advances timing of puberty in rats
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8
Q

KISS1R knockout mice have ____ GnRH neurons but ____ and ____

A

KISS1R knockout mice have normal GnRH neurons but gonadotropin deficiency and no puberty (hypogonadotropic hypogonadism)

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9
Q

KISS1 protein activates ___

A

KISS1 protein activates GPR54/KISS1R

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10
Q

TAC3 encodes ____

A

TAC3 encodes TACR3 / NKB receptor

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11
Q

____ acts upstream to release of kisspeptin, so mutations lead to ____ then ____

A

Neurokinin B acts upstream to release of kisspeptin, so mutations lead to hypogonadism than reversal in adulthood

(important for puberty, not reproduction)

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12
Q

____, ____, ____, and ____ are regulators / modulators of the hypothalamic-pituitary-gonadal axis

A

Gonadal steroids (T or E), metabolic hormones (leptin, ghrelin), sleep, and overall energy balance are regulators / modulators of the hypothalamic-pituitary-gonadal axis

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13
Q

Anorexia nervosa involves ____

A

Anorexia nervosa involves inadequate energy balance that suppresses production of GnRH, LH, and FSH

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14
Q

___ is important in the development / function of GnRH producing neurons

A

KAL1 / ANOS1 is important in the development / function of GnRH producing neurons

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15
Q

Excitatory regulation of onset of puberty occurs via ____, ____, ____, and ____

A

Excitatory regulation of onset of puberty occurs via leptin, KISS1 / GPR54, neurokinin B, and adequate energy balance

(KAL1 / ANOS1 -> development / function of GnRH-producing neurons)

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16
Q

Inhibitory regulation of onset of puberty occurs via ____, ____, and ____

A

Inhibitory regulation of onset of puberty occurs via GABA, beta endorphin, and MRKN3

(KAL1 / ANOS1 -> development / function of GnRH-producing neurons)

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17
Q

Describe puberty (gonadarche)

A

Puberty (gonadarche)

  • Sexual maturation
  • Reproductive capability
  • More accurately described as gonadarche
  • Maturation of hypothalamic / pituitary / gonadal axis
  • Inbcrease in GnRH, LH, FSH, and testosterone or estrogen / estradiol
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18
Q

Adrenarche is ____

A

Adrenarche is maturation of the hypothalamic-pituitary-adrenal axis

  • Andrenal androgens increase (DHE, DHEA-S, androstenedione)
  • Independent of puberty
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19
Q

Puberty (gonadarche) and adrenarche are ___ but ___

A

Puberty (gonadarche) and adrenarche are temporally related but independent

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20
Q

Describe adrenarche, pubarche, gonadarche, and menarche

A
  • Adrenarche: adrenal maturation
  • Pubarche: presence of pubic hair
  • Gonadarche: onset of gonadal maturation (true puberty)
  • Menarche (onset of menses)
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21
Q

Describe pubertal labs

A

Pubertal labs

  • LH: 0.3-15 mIU / mL
  • FSH: 0.8-11 mIU / mL
  • Estradiol: 16-300 pg / mL
  • Testosterone: 10-1000 ng / dL
  • DHEA-S: 90-300 mcg/dL
22
Q

First sign of central puberty (gonadarche) in girls is ____

A

First sign of central puberty (gonadarche) in girls is breast development (thelarche)

23
Q

First sign of central puberty (gonadarche) in boys is ____

A

First sign of central puberty (gonadarche) in boys is testicular enlargement

24
Q
A
25
Q

___ promote pubic hair, axillary hair, body odor, and acne in puberty

A

Androgens promote pubic hair, axillary hair, body odor, and acne in puberty

  • Predominantly adrenal androgens, particularly in girls
  • Some from gonadal testosterone in boys
  • Presence of pubic hair is called pubarche (not adrenarche unless DHEA-S is elevated into adrenarche range)
26
Q

Describe puberty in girls

A

Puberty in girls

  • Average pubertal onset: 10 years
  • Range of normal: 8-13 years old
  • Menarche average: 12.5 years
  • Peak growth rate: Tanner 2-3
  • Menarche: Tanner 4 breast development
27
Q

Describe puberty in boys

A

Puberty in boys

  • Average pubertal onset: 11.5 years
  • Range of normal onset: 9-15 years
  • Gynecomastia: Tanner 2-3
  • Voice change: Tanner 3-4
  • Peak growth rate: Tanner 4
  • Spermarche: Tanner 3-4
  • Facial hair: Tanner 4-5
28
Q

Puberty starts ____ in boys than girls

A

Puberty starts later in boys than girls

29
Q

Variations of normal puberty are ____, ____, ____, and ____

A

Variations of normal puberty are premature thelarche, premature, pubarche, premature adrenarche, and constitutional delay of puberty

30
Q

Precocious puberty is ____ in girls and ____ in boys

A

Precocious puberty is < 8 years in girls and < 9 years in boys

31
Q

Delayed puberty is ____ in girls and ____ in boys

A

Delayed puberty is > 13 years in girls and > 15 years in boys

(delayed puberty is also defined by an elapsed time of > 4 years from the onset of puberty to menarche or full testicular development)

32
Q

Describe evaluation of puberty

A

Evaluation of puberty

  • History: congenital anomalies, other endocrine or medical problems
  • Family history of pubertal onset
  • Physical examination
  • Bone age
  • Laboratory evaluation ± provacative testing
  • Imaging: MRI of pituitary and hypothalamus, ultrasound / MRI / CT of gonads / pelvis / adrenal glands as indicated
33
Q

Central precocious puberty is ____, involving ____ and ____

A

Central precocious puberty is GnRH dependent, involving pubertal LH / FSH and testosterone or estradiol

  • Idiopathic
  • CNS abnormalities: acquired, congenital, tumors, chronic exposure to sex steroids
34
Q

Peripheral precocious puberty is ____, involving ____ and ____

A

Peripheral precocious puberty is GnRH independent, involving low/prepubertal LH / FSH and pubertal / high testosterone or estradiol

  • Genetic (LH receptor activating mutations, McCune Albright syndrome)
  • Tumors
  • Other
35
Q

____ is a common cause of peripheral precocious puberty

A

McCune Albright syndrome is a common cause of peripheral precocious puberty

Peripheral precocious puberty is GnRH independent, involving low/prepubertal LH / FSH and pubertal / high testosterone or estradiol

36
Q

McCune Albright syndrome classic triad is ____, ____, and ____

A

McCune Albright syndrome classic triad is peripheral precocious puberty, cafe au lait spots, and polyostotic fibrous dysplasia

  • Peripheral precocious puberty: episodic ovarian cysts in girls
  • Polyostotic fibrous dysplasia: bone dysplasia
  • Can have hyperfunction of other hormones: TSH, GH, ACTH
37
Q

Gonadotropin levels will be ____ in central precocious puberty

A

Gonadotropin levels will be pubertal in central precocious puberty

38
Q

Sex steroid levels are ___ in central precocious puberty

A

Sex steroid levels are pubertal in central precocious puberty

39
Q

Gonadotropin levels are ____ in peripheral precocious puberty

A

Gonadotropin levels are prepubertal in peripheral precocious puberty

40
Q

Sex steroid levels are ____ in peripheral precocious puberty

A

Sex steroid levels are pubertal in peripheral precocious puberty

41
Q

Central precocious puberty has pubertal levels of ____ and ____

A

Central precocious puberty has pubertal levels of gonadotropins and sex steroids

42
Q

Peripheral precocious puberty involves prepubertal (low levels) of ____ but pubertal ____

A

Peripheral precocious puberty involves prepubertal (low levels) of gonadotropins but pubertal sex steroids

43
Q

Delayed puberty may be caused by ____

A

Delayed puberty may be caused by hypogonadotropic hypogonadism

44
Q

Hypogonadotropic involves the ____, ____, and ____ and causes ____ and ____

A

Hypogonadotropic involves the central, hypothalamic, and pituitary, and causes low / prepubertal LH / FSH and low testosterone or estradiol

45
Q

____ is a common cause of hypogonadotropic hypogonadism

A

Kallmann syndrome is a common cause of hypogonadotropic hypogonadism

46
Q

Describe Kallmann syndrome

A

Kallmann syndrome

  • Hypogonadotropic hypogonadism due to failure of the GnRH neuron and olfactory placode migration
  • X-linked most commonly caused by mutations in KAL1 (ANOS1) gene
  • Can also be autosomal dominant
  • Anosmia
  • Other possible findings: coloboma, synkinesis (mirror image movements), hearign loss, single kidney
47
Q

Delayed puberty may be caused by ____

A

Delayed puberty may be caused by hypergonadotropic hypogonadism

48
Q

Hypergonadotropic is ____ and involves ____ and ____

A

Hypergonadotropic is primary / gonadal and involves very high LH / FSH and low testosterone or estradiol

  • Acquired
  • Congenital
49
Q

A 16 year old girl had thelarche at 11 years old but has not had menarche yet. Is this delayed puberty?

A

A 16 year old girl had thelarche at 11 years old but has not had menarche yet. Is this delayed puberty?

Yes

50
Q

A 16 year old boy has 2 mL testes, Tanner 1 pubic hair, no voice change and no body odor. Is this delayed puberty?

What diagnoses are on your differential?

A

A 16 year old boy has 2 mL testes, Tanner 1 pubic hair, no voice change and no body odor. Is this delayed puberty?

Yes

What diagnoses are on your differential?

Hypogonadotropic hypogonadism: Kallmann syndrome, optic nerve hypoplasia, chronic illness, tumor, h/o radiation treatment, malnutrition, elevated prolactin or cortisol

51
Q

If LH and FSH are very high and testosterone, what diagnoses are on your differential?

A

If LH and FSH are very high and testosterone, what diagnoses are on your differential?

  • Cognenital: Klinefelter syndrome, gonadal dysgenesis
  • Anatomic: anorchia, bilateral testicular torsion
  • Acquired: chemotherapy, radiation treatment, infectious (mumps)