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Hormones > Endo 9: Endocrine Infertility > Flashcards

Endo 9: Endocrine Infertility Flashcards

1
Q

Outline the hypothalamo-pituitary-gonadal axis for men

A

GnRH –> FSH and LH –> Testosterone. Leydig cells release testosterone, which negatively feeds back to hypo. and pit. Sertoli cells, responsive to FSH, release inhibin negatively feedback on pit. and hypothalamus

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2
Q

Outline the hypothalamo-pituitary-gonadal axis for females

A

GnRH –> FSH/LH –> oestreogen. Negative feedback on hypothalamus and pituitary…. however at high concentration, the OESTRADIOL actually has positive feedback ON THE HYPOTHALAMUS –> INCREASED GnRH–> (FSH) and LH surge and ovulation!

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3
Q

3 stages of 28 day menstrual cycle

A

Follicular phase, ovulation and luteal phase

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4
Q

Define infertlity

A

Infertility: inability to conceive after 1 year of regular unprotected sex.

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5
Q

How many couples affected by infertlilty

A

1:6

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6
Q

What proportion caused by males, females, or unknown

A 
in males (30%)
or females (45%)
or unknown (25%)
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7
Q

Outline primary gonadal failure

A

Ovary/testes not working.

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8
Q

Outline secondary hypo/pituitary disease

A

Low LH/FSH and thus low testosterone and oestradiol

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9
Q

Male hypogonadism clinical featrures

A

Loss of libido, impotence, small testes, decrease muscle bulk, osteoporosis

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10
Q

Cause of male hypogonadism

A

HYPOTHALAMC-PITUITARY DISEASE:

  • Hypopituitarism
  • Kallmans syndrome (low GnRH as neurones havent developed properly)
  • Illness/underweight

PRIMARY GONADAL DISEASE

  • Congenital: Klinefelters syndrome (XXY)
  • Acquired: Testicular torsion, Chemotherapy

SECONDARY: HYPERPROLACTINAEMIA

OTHER: ANDROGEN RECEPTOR DEFICIENCY (congenital- testosterone can’t act on the receptor)

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11
Q

Clinical features of Kallman’s syndrome

A

small penis (micropenis) and undescended testes (cryptorchidism), lack of sense of smell (anosmia)

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12
Q

Investigations for male hypogonadism

A

LH, FSH, testosterone (if all low –> MRI pitutary )

Prolactin (in case prolactinoma means that GnRH is suppressed)

Sperm count
Azoospermia = absence of sperm in ejaculate
Oligospermia = reduced numbers of sperm in ejaculate

Chromosomal analysis (Klinefelters XXY)

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13
Q

Treatment for male hypogonadism

A

Replacement testosterone for all patients (for symptoms, not fertility)

For fertility: if hypo / pit disease 
sc gonadotrophins (LH & FSH) (as testosterone won't stimulate spermatogenesis)

Hyperprolactinaemia – dopamine agonist

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14
Q

Where are androgens produced

A
  1. interstitial Leydig cells of the testes
  2. adrenal cortex (males and females)
  3. ovaries
  4. placenta
  5. tumours
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15
Q

Main actions of testosterone

A
  1. development of the male genital tract
  2. Maintains fertility in adulthood
  3. Control of secondary sexual characteristics
  4. Anabolic effects (muscle, bone)
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16
Q

How does testosterone travel in the circulation

A

98% protein bound)

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17
Q

In what forms does testosterone act on receptors

Where are ER receptors found

A

Androgen receptor (if testosterone converted by 5a-reductase to DHT)

Estrogen receptor (if testosterone converted to 17b-oestradiol (E2) by aromatase)

ER and AR are nuclear receptors

ER (oestrogen receptor) in brain and adipose tissue

18
Q

Clinical use of testosterone

A

lean body mass
muscle size and strength
bone formation and bone mass (in young men)
libido and potency

WILL NOT RESTORE FERTILITY WHICH REQUIRES TREATMENT WITH GONADOTROPHINS

19
Q

State the 3 categories of fertility disorders in females

A
  1. Amenorrhoea
  2. Polycystic Ovarian Syndrome (PCOS)
  3. Hyperprolactinaemia
20
Q

Differentiate Primary amenorrhoea and Secondary amenorrhoea and what is oligoenorroea

A

P: failure to begin spontaneous menstruation by age 16 years

S:absence of menstruation for 3 months in a woman who has previously had cycles

Oligomenorrhoea = irregular long cycles

21
Q

Causes of amenorrhoea

A

Pregnancy / Lactation (due to high prolactin which inhibits GnRH)

Ovarian failure:

  • premature ovarian failure
  • Ovariectomy / chemotherapy
  • ovarian dysgenesis (Turners 45 XO) – lacking one chromosome

Gonatrophin failure:

  • Hypo / pit disease
  • Kallmann’s syndrome (anosmia, Low GnRH)
  • Low BMI
  • Post pill amenorrhoea

Hyperprolactinaemia

Androgen excess: gonadal tumour

22
Q

Turners clinical effects

A 
short stature
cubitus valgus (wide carrying angle)
gonadal dysgenesis
23
Q

Investigation of amenorrhoea

A

Pregnancy test

LH, FSH, oestradiol

Day 21 progesterone (will be high if ovulating-as corpus luteum will produce, if low then there isn’t ovulation)- NOTE THIS IS ONE OF TWO WAYS OF TESTING IF THERE HAS BEEN OVULATION (the other is ultrasound scan for corpus luteum)

Prolactin, thyroid function tests

Androgens (testosterone, androstenedione, DHEAS)

Chromosomal analysis (Turners 45 XO)

Ultrasound scan ovaries / uterus

24
Q

Treatment of amenorrhoea

A

Treat the cause (eg low weight)

Primary ovarian failure – infertile so don’t give gonadotropns, give HRT for symptoms due to lack of oestrogen and progesterone (not good in terms of bones)

Hypothalamic / pituitary disease

  • HRT for oestrogen replacement
  • Fertility: Gonadotrophins (LH & FSH) – part of IVF treatment
25
Q

Incidence of PCOS

A

1 in 12 women of reproductive age

26
Q

What is PCOS associated with

A

increased cardiovascular risk and insulin resistance (>diabetes) ? why

27
Q

How is a PCOS diagnosis made

A

2 from:

  • polycystic ovaries on USS
  • oligo- / anovulation
  • clinical / biochemical androgen excess
28
Q

Clinical features of PCOS

A

Hirsuitism

Menstrual cycle disturbance

Increased BMI

29
Q

How to treat PCOS for fertility

A

Metformin (for insulin resistance and diabetes)

Clomiphene

Gonadotrophin therapy as part of IVF treatment

30
Q

Mechanism of action of clomiphene

A

anti-oestrogenic in the hypothalamo-pituitary axis

Bind to oestrogen receptors in the hypothalamus thereby blocking the normal negative feedback, resulting in an increase in the secretion of GnRH and gonadotrophins

(SERM!)

31
Q

Outline control of prolactin secretion

A

Dopamine inhibits prolactin, TRH stimuates it

Suckling suppresses dopamien release increasing prolactin release

32
Q

How does prolactin affect other hormones

A

GnRH pulsatlity (-)

LH actions on ovary / testis (-)

33
Q

Causes of hyperprolactinaemia

A

Dopamine antagonist drugs
Anti-emetics (metoclopramide)
Anti-psychotics (phenothiazines)

Prolactinoma

Stalk compression due to pituitary adenoma (i.e. dopamine from hypothalamus can’t reach the pituitary)

PCOS

Hypothyroidism

Oestrogens (OCP), pregnancy, lactation,

Idiopathic

34
Q

Why is prolactin preventing pregnancy

A

To stop immediate pregnancy after breastfeeding etc.

35
Q

Clinical features of Hyperprolactinaemia

A

Galactorrhoea

Reduced GnRH secretion / LH action&raquo_space; hypogonadism

Prolactinoma

  • Headache
  • Visual field defect
36
Q

Treatment of Hyperprolactinaemia

A

Treat the cause – stop drugs

Dopamine agonist

  • Bromocriptine
  • Cabergoline

Prolactinoma

  • Dopamine agonist therapy
  • Pituitary surgery rarely needed
37
Q

Levels of GnRH, FSH/LH and oestrogen/testosterone in primary gonadal failure

A

High GnRH and high LH and FSH because of lack of negative feedback,

Low testosterone and oestradiol

38
Q

Testosterone supports spermatogenesis, why can it not be given alone to treat infertility in males

A

pharmacological testosterone replacement this will downregulate their LH & Fsh and switch off spermatogenesis. Hence need gonadotropins which will also downstream more physiologically stimulate testosterone release

39
Q

T/f treatment with testosterone will restore fertility in male

A

It will not restore fertility, which requires treatment with gonadotrophins to restore normal spermatogenesis

40
Q

How is GnRH released

A

In pulses, every 90 minutes or so

This is switched off by prolactin

41
Q

T/f prolactin increases following pregnancy to stimulate milk production. Because this inhibits GnRH, periods stop after pregnancy

A

F….. periods do not stop…. it’s weakly contraceptive

Hormones (23 decks)

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