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LCRS Endocrinology > Endocrine infertility > Flashcards

Endocrine infertility Flashcards

1
Q

What stimulates release of LH and FSH from the pituitary?

A

GnRH pulses from the hypothalamus

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2
Q

What does LH stimulate?

A

Testosterone production in the testes

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3
Q

Which cells does LH specifically stimulate to produce testosterone?

A

Leydig cells

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4
Q

What is testosterone responsible for?

A

Secondary sexual characteristics and aids spermatogenesis

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5
Q

Where does FSH stimulate (including cells)?

A

Sertoli cells in seminiferous tubules -> sperm and inhibin A and B

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6
Q

What does testosterone have a negative feedback effect on?

A

Hypothalamus and pituitary

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7
Q

What does inhibin have a negative feedback effect on?

A

Pituitary FSH secretion

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8
Q

What are the three phases of the menstrual cycle?

A

Follicular phase
Ovulation
Luteal phase

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9
Q

What does LH stimulate in the ovaries?

A

Production of progesterone and oestradiol

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10
Q

What does FSH develop?

A

Follicles and inhibin

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11
Q

After day 10, what happens in terms of follicles?

A

The leading follicle develops into the Graffian follicle

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12
Q

What is the initial effect of oestrogen on LH and FSH?

A

It inhibits their secretion

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13
Q

In the follicular phase, how does a man and woman’s HPG axis compare?

A

They are pretty much the same

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14
Q

When does the effect of oestrogen switch from negative feedback to positive feedback?

A

Once oestrogen levels reach a certain point

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15
Q

How does oestrogen have a positive feedback effect?

A

Increases GnRH release

Increases LH sensitivity to GnRH

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16
Q

What does the positive feedback effect of oestrogen lead to?

A

A mid cycle LH surge which triggers ovulation from the leading follicle

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17
Q

What is the definition of infertility?

A

Inability to conceive after 1 year of regular unprotected sex

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18
Q

How many couples are affected?

A

1/6

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19
Q

What percentage of infertility is caused by abnormalities in men?

A

30%

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20
Q

What percentage of infertility is caused by abnormalities in women?

A

45% (other 25% is unknown)

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21
Q

What happens in primary gonadal failure?

A

Testes or ovaries are not producing testosterone/oestrogen so there’s no negative feedback on HPG axis meaning you get high GnRH and high LH/FSH

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22
Q

What happens in pituitary disease?

A

Inability of the pituitary gland to produce FSH and LH so their levels are low and as a result there is low oestradiol and testosterone

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23
Q

What are the clinical features of male hypogonadism?

A 
Loss of libido
Impotence
Small testes
Decreased muscle bulk
Osteoporosis
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24
Q

What are the causes of male hypogonadism?

A

Hypothalamic/pituitary disease
Hypopituitarism
Kallmann syndrome (anosmia and low GnRH)
Illness/underweight- mainly due to low levels of leptin

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25
Q

What is an example of congenital primary gonadal disease?

A

Klinefelter’s syndrome

26
Q

What is an example of acquired primary gonadal disease?

A

Testicular torsion, chemotherapy

27
Q

What is the effect of hyperprolactinaemia on the gonads?

A

Inhibits function

28
Q

How do you test for male hypogonadism?

A

Check LH, FSH and testosterone - if they’re all low, MRI the pituitary to check for pituitary problem
Check prolactin
Check sperm count

29
Q

What is azoospermia?

A

Absence of sperm in ejaculate

30
Q

What is oligospermia?

A

Reduced number of sperm in ejaculate

31
Q

How do you treat male hypogonadism?

A

Replacement testosterone for all patients- increase muscle bulk and protect against osteoporosis
If they have hypothalamic/pituitary disease- Gonadotrophin injections to stimulate testosterone production
To treat hyperprolactinaemia, you need a dopamine agonist as dopamine is main influence on prolactin release and it has a negative effect

32
Q

What are the endogenous sites of production of androgens?

A 
Interstitial Leydig cells of the testes
Adrenal cortex
Ovaries
Placenta
Tumours
33
Q

What are the main actions of testosterone?

A

Development of the male genital tract
Maintains fertility in adulthood
Control of secondary sexual characteristics
Anabolic effects

34
Q

How does testosterone exist in the blood?

A

Heavily bound 98%

35
Q

What does dihydrotestosterone act on?

A

Androgen receptors

36
Q

How is dihydrotestosterone formed?

A

Testosterone is converted by 5 alpha-reductase

37
Q

What does aromatase convert testosterone to?

A

17beta-oestradiol

38
Q

What does 17beta-oestradiol act on?

A

Oestrogen receptors

39
Q

In adulthood, what does testosterone increase?

A

Lean body mass
Muscle mass and strength
Bone formation and mass
Libido and potency

40
Q

What are the three main gonadal disorders in women?

A

Amenorrhoea
Polycystic ovarian syndrome (PCOS)
Hyperprolactinaemia

41
Q

What is amenorrhoea?

A

Absence of periods

42
Q

What is primary amenorrhoea?

A

Failure to develop spontaneous menstruation by the age of 16 years

43
Q

What is secondary amenorrhoea?

A

Absence of menstruation in a women for 3 months who has previously had menstrual cycles

44
Q

What is oligomenorrhoea?

A

Irregularly long cycles

45
Q

What are the causes of amenorrhoea?

A 
Pregnancy
Lactation 
Ovarian failure
Premature ovarian sufficiency
Oophorectomy
Chemotherapy
Ovarian dysgenesis (Turner's syndrome 45X)
Hypothalamic/pituitary disease
Kallmann's syndrome
Low BMI
Post-pill amenorrhoea
46
Q

What are some features of Turner’s syndrome?

A

Short stature
Cubitus valgus
Gonadal dysgenesis

47
Q

What is cubitus valgus?

A

When the forearm is angled away from the body to a greater degree than normal when fully extended

48
Q

After how long are you advised to stop the pill and why?

A

4 years and because if you use the pill for a long time then your periods won’t come back for around 12 months

49
Q

How would you investigate amenorrhoea?

A 
Pregnancy test
Check LH, FSH and oestradiol
Day 21 progesterone- should be a rise around this time
Prolactin
Thyroid function
Androgens
Chromosomal analysis
Ultrasound scan
50
Q

How do you treat amenorrhoea?

A

Treat the cause

Primary ovarian failure and hypothalamic/pituitary disease- HRT

51
Q

What proportion of women of reproductive age are affected by PCOS?

A

1/12

52
Q

What is PCOS associated with?

A

Increased cardiovascular risk and diabetes

53
Q

What is the criteria to diagnose PCOS?

A

Need two of the following:
Polycystic ovaries on ultrasound
Oligoovulation/anovulation
Clinical/biochemical androgen excess

54
Q

What are the clinical features of PCOS?

A

Hirsutism
Menstrual cycle disturbance
Increased BMI

55
Q

How is PCOS treated?

A

Metformin- Insulin sensitiser used in type II diabetes
Clomiphene- Anti-oestrogen effect in hypothalamic-pituitsry axis. Binds to oestrogen receptors blocking negative feedback. Results in increased GnRH and gonadotrophins

56
Q

What is the main influence on prolactin release?

A

Dopamine- negative effect

57
Q

What is the effect of TRH on prolactin release?

A

Mild stimulatory

58
Q

What does prolactin stimulate?

A

Production of milk in lactating women

59
Q

What does prolactin have a negative feedback effect on?

A

GnRH pulsatility and LH actions on ovaries and testes

60
Q

What are the main causes of hyperprolactinaemia?

A 
Dopamine antagonists
Prolactinoma
Stalk compression due to pituitary adenoma
PCOS
Hypothyroidism
Oestrogen (pill), pregnancy, lactation
Idiopathic
61
Q

What are the clinical features of hyperprolactinaemia?

A

Galactorrhea
Reduced GnRH secretion/LH action leads to hypogonadism
Prolactinoma- headache and visual defects

62
Q

How do you treat hyperprolactinaemia?

A

Treat the cause- stop the drugs if that is what is causing it
Dopamine agonists- cabergoline and bromocriptine
Will also cause decrease in size of a prolactinoma

LCRS Endocrinology (18 decks)

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