Endocrine Infertility Flashcards
Which cells within the testes does LH stimulate and what does it make these cells produce?
Leydig Cells Produce testosterone (secondary sexual characteristics + aids spermatogenesis)
Which cells within the testes does FSH stimulate and what does it makes these cells produce?
Sertoli cells (in seminiferous tubules) Produce sperm + inhibin A + B
What does inhibin inhibit?
Pituitary FSH secretion
What are the 3 phases of the menstrual cycle?
Follicular Phase
Ovulation
Luteal Phase
What does LH stimulate in the ovaries?
Oestradiol + progesterone production
What does FSH stimulate in the ovaries?
Follicular development + 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 + LH
What does the leading follicle develop into by around day 10?
Graffian Follicle
Once oestrogen reaches a certain level it switches to positive feedback. How does it do this?
It increases GnRH secretion
It increases LH sensitivity to GnRH
Causes mid cycle LH surge leading to ovulation
Define infertility.
Inability to conceive after 1 year of regular unprotected sex
What is primary gonadal failure and what effects does it have on the HPG axis?
A problem with the gonads
Testes/ovaries don’t produce enough testosterone/oestrogen so there is no negative feedback on the HPG axis resulting in high GnRH, LH + FSH.
Describe the levels of the different hormones in the HPG axis in the case of hypothalamic/pituitary disease causing infertility.
Low GnRH
Low FSH
Low LH
State 5 clinical features of male hypogonadism.
Loss of libido Impotence Small testes Decreased muscle bulk Osteoporosis (testosterone has anabolic action in the bone)
State 6 causes of male hypogonadism.
Hypopituitarism Kallmann’s Syndrome (anosmia + low GnRH) Illness/underweight Primary gonadal disease Hyperprolactinaemia Androgen receptor deficiency (RARE)
State congenital and acquired causes of primary gonadal disease.
Congenital: Klinefelter’s Syndrome (XXY)
Acquired: Testicular torsion, chemotherapy
What are the main investigations for male hypogonadism?
LH, FSH + testosterone (if all low- MRI to check pituitary problem)
Prolactin
Sperm count (azoospermia: absence of sperm in ejaculate; oligospermia: reduced number of sperm in ejaculate)
Chromosomal analysis (Klinefelter’s= XXY)
What is given to all patients with hypogonadism?
Testosterone to increase muscle bulk + protect against osteoporosis
How do you restore fertility in someone with hypothalamic/pituitary disease?
Subcutaneous gonadotrophin injections to stimulate testosterone release
What is the treatment for hyperprolactinaemia?
Treat cause- stop drugs
Dopamine agonists – bromocriptine + cabergoline
Pituitary surgery (rarely used because drugs normally works well)
State 5 endogenous sites of production of androgens.
Interstitial leydig cells in the testes Adrenal cortex Ovaries Placenta Tumours
What are the 4 main actions of testosterone?
Development of the male genital tract Maintains fertility in adulthood Control of secondary sexual characteristics Anabolic effects (muscle, bone)
Testosterone is heavily plasma protein bound and it can be converted to other hormones in various tissues. State 2 products that testosterone can be converted to and the enzymes responsible for these conversions.
Converted by 5-alpha-reductase to dihydrotestosterone (DHT), which acts on androgen receptors
Converted by aromatase to 17-beta-oestradiol, which acts on oestrogen receptors
What type of receptors does DHT and E2 act on?
Nuclear receptors
What are the clinical uses of testosterone?
Increase lean body mass Increase muscle size + strength Bone formation + bone mass Libido + potency (Does NOT restore fertility)
