Endocrine infertility Flashcards
How long is the menstrual cycle and what are the phases
28 days
Follicular phase
Ovulation
Luteal phase
Describe the regulation of sex hormone release in males
- Hypothalamus releases GnRH
- Adenohypophysis releases LH and FSH
- Testis produces testosterone
- Testosterone has a negative feedback effect on the hypothalamus, also due to inhibit production (pituitary)
Describe the regulation of sex hormone release in females during the follicular phase
- Hypothalamus releases GnRH
- Adenohypophysis releases LH and FSH
- Ovary produces oestradiol and progesterone
- Inhibit produces negative feedback effect on pituitary and hypothalamus
Describe the regulation of sex hormone release in females during the ovulation
- Hypothalamus releases GnRH
- Adenohypophysis releases a surge of LH and some FSH
- Ovary releases oestradiol as it undergoes ovulation
- Oestradiol causes a positive feedback effect on the hypothalamus
What is the significance of implantation in the luteal phase
implantation does not occur - endometrium is shed -> menstruation
Implantation does occur -> pregnancy
Define infertility
Inability to conceive after a year of regulation unprotected sex
What are the proportion of people where infertility is caused by abnormalities
Males - 30%
Females - 45%
Unknown - 25%
How many couples does infertility affect
1:6
How does primary gonadal failure cause infertility
Low testosterone / oestradiol
High GnRH and High LH and FSH due to lack of negative feedback
How does hypopituitary disease cause infertility
Low testosterone and oestradiol
Low LH and FSH released by the pituitary gland
What are the clinical features of male hypogonadism
Loss of libido Impotence Small testes Decreased muscle bulk Osteoporosis
What are the causes of male hypogonadism
Hypothalamic-pituitary disease:
Hypopituitarism
Kallmans syndrome (anosmia and low GnRH)
Illness/underweight
Primary gonadal disease:
Congenital - Klinefelters
Acquired: testicular torsion, chemo
Hyperprolactinaemia
Androgen receptor deficiency
What are the investigations carried out for male hypogonadism
LH, FSH , testosterone
All low -> MRI pituitary
Prolactin
Sperm count
Chromosomal analysts i.e. for Klinefelters
What is azoospermia
Absence of sperm in ejaculate
What is oligospermia
Reduced numbers of sperm in ejaculate
What is the treatment for male hypogonadism
Replacement testosterone for all
Fertility: subcutaneous gonadotrophin (LH and FSH)
Hyperprolactinaemia: dopamine agonist
What are the endogenous sites of production of androgens
Interstitial Leydig cells of the testes Adrenal cortex Ovaries Placenta Tumours
What are the main action of testosterone
Development of the male genital tract Maintains fertility in adulthood Control of secondary sexual characteristics Anabolic effects (muscle, bone)
How is testosterone converted to dihydrotestosterone
98% protein bound circulating testosterone is converted to dihydrotestosterone via 5alpha-reductase
How is testosterone converted to 17beta-oestradiol (E2)
98% protein bound testosterone is converted to 17b-oestradiol via aromatase
How does DHT and E2 act
via nuclear receptors
DHT - androgen receptor
E2 - oestrogen receptor e.g. brain and adipose tissue
What is the difference between amenorrhoea, primary amenorrhoea, secondary amenorrhoea and oligomenorrhoea
Amenorrhoea - absence of periods
Primary amenorrhoea - failure to begin spontaneous menstruation by 16
Secondary amenorrhoea - absence of menstruation for 3 months in a woman who has previously had cycles
Oligomenorrhoea - irregular long cycles
What are the causes of amenorrhoea
Pregnancy Lactation Ovarian failure (premature ovarian failure, ovariectomy, chemo, ovarian dysgenesis, Turner's) Gonadotrophin failure Hyperprolactinaemia Androgen excess (gonadal tumour)
Describe Turner’s syndrome
Missing one X chromosome (45)
Short stature
Cubitus valgus
Gonadal dysgenesis
