9 - endocrine infertility Flashcards
What is produced from the hypothalamus that stimulates the release of FSH and LH from the pituitary?
GnRH
Which cells within the testes does LH stimulate and what does it make these cells produce?
Leydig Cells
are stimulated to produce testosterone
Which cells within the testes does FSH stimulate and what does it makes these cells produce?
Sertoli cells (in the seminiferous tubules) are stimulated to produce sperm and inhibin A and B
What is the role of testosterone in the male hypothalamus-pituitary-gonadal axis?
responsible for secondary sexual characteristics and aids spermatogenesis
has a negative feedback on the hypothalamus and pituitary
What does inhibin inhibit?
Pituitary FSH secretion
What are the three phases of the menstrual cycle?
Follicular Phase
Ovulation
Luteal Phase
What does LH stimulate in the ovaries?
Oestradiol and progesterone production
What does FSH stimulate in the ovaries?
Follicular development and inhibin production
What effect does oestrogen have on the HPG axis in the follicular phase of the menstrual cycle?
It has a negative feedback effect – inhibits FSH and LH
What does the leading follicle develop into by around day 10?
Graffian Follicle
What effect does oestrogen have on the HPG axis in the follicular phase of the menstrual cycle?
It has a negative feedback effect – inhibits FSH and LH
Once oestrogen reaches a certain level it switches to positive feedback. How does it do this?
What affect does this have on other hormones and why is this necessary?
It increases the GnRH secretion
It increases LH sensitivity to GnRH
Leads to mid-cycle LH surge which is needed for egg maturation and ovulation
Define primary gonadal failure
defect/failure of the gonads (testes/ovaries)
testes/ovaries don’t produce enough testosterone/
If you did a blood test on someone with primary gonadal failure, what would the levels of hormones in the blood be?
high GnRH
high FSH and LH
(testes/ovaries are not producing testosterone/oestrogen so there is no negative feedback)
Define infertility.
Inability to conceive after 1 year of regular unprotected sex
Describe the levels of the different hormones in the HPG axis in the case of hypothalamic/pituitary disease causing infertility.
(is this secondary/tertiary hypogonadism)
Low GnRH
Low FSH
Low LH
(low oestrodiol and testosterone)
State some of the clinical features of male hypogonadism.
Loss of libido Impotence Small testes Decreased muscle bulk Osteoporosis (testosterone has anabolic action in the bone)
State 5 causes of male hypogonadism
- Hypopituitarism
- Kallmann’s Syndrome (anosmia + low GnRH)
- Primary Gonadal Disease
- Illness/underweight
- Hyperprolactinaemia
- Androgen receptor deficiency (RARE)