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LCRS Endocrinology > 9. Endocrine Infertility > Flashcards

9. Endocrine Infertility Flashcards

1
Q

Male Hypothalamo-Pituitary-Gonadal Axis

A
  • GnRh pulses from the hypothalamus, stimulating the release of LH and FSH from the pituitary
  • Lh then stimulates testosterone production in the testes- Leydig cells
  • Testosterone aids spermatogenesis and secondary sexual characteristics
  • FSH -> sertoli cells -> Sperm + Inhibin A,B
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2
Q

THREE phases of the menstrual cycle

A
  1. Follicular phase
  2. Ovulation
  3. Luteal phase
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3
Q

Female Hypothalamo-Pituitary-Gonadal Axis in FOLLICULAR PHASE

A

LH stimulates production of oestrodiol and progesterone

FSH stimulates follicular development and inhibin

  • Leading follicle becomes the GRAFFIAN FOLLICLE after around day 10
  • Oestrogen initially inhibits LH and FSH secretion
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4
Q

Female Hypothalamo-Pituitary-Gonadal Axis in LUTEAL PHASE

A

Once the oestrogen reahces a threshold, it switches from negative feedback to positive feedback

It increases GnRH release and increases LH sensitivity to GnRH

This leads to a mid-cycle LH surge which triggers ovulation

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5
Q

Infertility definition

A

Inability to concieve after 1 year of regular unprotected sex

1/6 couples affected

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6
Q

Primary Gonadal Failure features

A

A defecit of the gonads

The testes or ovaries are not producing sex steroids so there is no feedback on the HPG axis SO you get high GnRH, LH and FSH

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7
Q

Clinical features of male hypogonadism

A
  • Loss of libido
  • Impotence
  • Small testes
  • Decreased muscle bulk
  • Osteoperosis (testosterone has an anabolic effect in the bones)
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8
Q

Causes of male hypogonadism

A
  1. Hypothalamic-Pituitary Disease
  • Hypopituitarism
  • Kallmann Syndrome (anosmia and low GnRH) presents as a failure to go through puberty and coincident anosmia (GnRH and olfactory neurones migrate forwards together
  • Underweight (due to low levels of leptin)
  1. Primary Gonadal Disease
  • Congenital= Klinefelters Syndrome (XYY)
  • Acquired= Testicular torsion, chemotherapy
  1. Hyperprolactinoma
  2. Androgen Receptor Deficiency (very RARE)
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9
Q

Investigations for Male Hypogonadism

A
  1. LH, FSH and Testosterone serum test- if low should be followed up by MRI of the pituitary
  2. Prolactin test- checking for hyperprolactinaemia
  3. Sperm count
  4. Chromosomal analysis- cheking for klinefelters (XYY
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10
Q

Azoospermia definition

A

Abscence of sperm in the ejaculate

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11
Q

Oligospermia definition

A

Reduced numbers of sperm in the ejaculate

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12
Q

Treatment of Male Hypogonadism

A
  • Replacement testosterone for all patients (will increase muscle bulk and protect against osteoperosis)

If hypothalamic/ pituitary disease:

  • Gonadotrophins to stimulate testosterone release- subcutaneous gonadotrophin

If Hyperprolactinaemia:

  • Dopamine agonist (prolactin inhibitor)
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13
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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14
Q

Circulating testosterone binding

A

Heavily protein bound (98%)

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15
Q

Tissue specific processing of testosterone

A

In different tissues you get testosterone being converted to other things:

  • 5 a-reductase converts testosterone to dihydrotestosterone (DHT) which acts on androgen receptors
  • Aromatase converts testosterone to 17B-oestradiol (E2) which acts via Oestrogen receptors

Both of these variants act on nuclear receptors

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16
Q

Testosteone in adulthod will increase

A
  • Lean body mass
  • Muscle size and strength
  • Bone formation and bone mass (in young men)
  • Libido and potency
  • It will NOT restore fertility, which requires treatment with gonadotrophins to restore normal spermatogenesis
17
Q

Characteristics of Amenorrhoea

A

Abscence of periods

Primary Amenorrhoea= failure to develop spontaneous menstruation by the age of 16 years

Secondary Amenorrhoea= abscence of menstruation for 3 months in a woman who has had previous cycles

18
Q

Oligomenorrhoea

A

Irregular long cycles

19
Q

Causes of amenorrhoea

A
  • PREGNANCY
  • Lactation
  • Ovarian Failure:
    • Early menopause
    • Oophorectomy
    • Ovarian dysgenesis (Turner’s syndrome)
  • Gonadotrophin failure:
    • Hypothalamic/ Pituitary disease
    • Kallmann’s syndrome
    • Low BMI
    • Post pill
    • Hyperprolactinaemia
20
Q

Investigations to identify causes of Amenorrhoea

A

Pregnancy test

LH, FSH and Oestradiol serum test (to identify gonadotrophin failure)

Day 21 Progesterone test:

  • Progesterone rises over a long time over the second half of the cycle
  • Should be a rise to indicate ovulation

Prolactin test

Thyroid function test- Hyper and hypo can cause problems with periods

Chromosomal analysis (turner’s)

Ultrasound

21
Q

Treatment of Amenorrhoea

A

Treat the cause:

Primary ovarian failure- HRT

Hypothalamic/ pituitary disease- HRT

22
Q

Polycystic Ovarian syndrome characteristics

A
  • Affects 1 in 12 women of reproductive age
  • Associated with:
    • Increased cardiovascular risk
    • Insulin resistence
23
Q

Criteria needed to diagnose Polycyctic Ovarian syndrome

A

Require TWO of the following:

  • Polycystic ovaries on the ultrasound scan
  • Oligoovulation/ anovulation
  • Clinical/ biochemical androgen excess
24
Q

Clinical features of polycystic syndrome

A
  • Hirtuism
  • Menstrual cycle disturbance
  • Increased BMI
25
Q

Treatment of PCOS- Fertility

A
  • Metiformin- Insulin sensitiser used in type II diabetes
  • Clomiphene- Anti-oestrogenic effect in the hypothalamo-pituitary axis- binds to O receptors therby blocking negative feedback- results in increased GnRH and gonadotrophin secretion
  • Gonadotrophin therapy
26
Q

Clinical features of Hyperprolactinaemia

A
  • Galactorhoea
  • Reduced GnRH secretion/ LH action leads to hypogonadism
  • Prolactinoma:
    • ​Headache
    • Visual field defect
27
Q

Treatment of Hyperprolactinaemia

A

Treat the cause - e.g. stop the drugs if that’s what’s causing it

  • Dopamine Agonists:
    • Bromocriptine
    • Cabergoline
    • This will also cause a decrease in the size of the tumour if it is being caused by a prolactinoma
  • Prolactinoma:
    • Dopamine agonist therapy
    • Pituitary surgery rarely needed (because drugs usually work)

LCRS Endocrinology (18 decks)

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