Endocrine infertility Flashcards
What are the phases of the menstrual cycle?
Follicular phase
Ovulation
Luteal phase
What are the possible outcomes of the luteal phase of the menstrual cycle?
If implantation does not occur, menstruation follows (shedding of endometrium).
If implantation occurs, pregnancy follows.
What is infertility?
Inability to conceive after 1 year of regular unprotected sex.
What are the clinical features of male hypogonadism?
Loss of libido Impotence Small testes Decreased muscle bulk Osteoporosis
What can male hypogonadism be caused by?
Hypothalamic/pituitary disease, e.g. hypopituitarism
Kallman’s syndrome (anosmia, low GnRH, low-normal stature, undescended testes)
Illness/underweight
Primary gonadal disease, e.g. Klinefelter’s syndrome (congenital, XXY), testicular torsion (acquired), chemotherapy (acquired)
Hyperprolactinaemia
Androgen receptor deficiency
What stimulates the release of LH and FSH from the pituitary in males?
GnRH pulses from the hypothalamus.
What does LH stimulate in males?
Testosterone production in Leydig cells of the testes.
What is the role of testosterone in males?
Secondary sexual characteristics
Aids spermatogenesis
Negative feedback on the hypothalamus and pituitary
What is the role of FSH in males?
Stimulates Sertoli cells in seminiferous tubules to produce sperm and inhibin A and B.
What is the role of inhibin in males?
Negative feedback on pituitary FSH secretion.
What does LH stimulate in females in the follicular phase of the menstrual cycle?
Production of oestradiol and progesterone in the ovaries.
What does FSH stimulate in females in the follicular phase of the menstrual cycle?
Follicular development.
Inhibin.
By around day 10 of the menstrual cycle, what has the leading follicle developed into?
Graffian follicle
What is the role of oestrogen in females in the follicular phase of the menstrual cycle?
Negatively inhibits LH and FSH secretion.
What happens in the luteal phase of the menstrual cycle?
Once the oestrogen levels reach a certain point, 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.
This triggers ovulation from the leading follicle.
What is primary gonadal failure?
A defect of the gonads.
The testes or ovaries are not producing testosterone/oestrogen so there is no negative feedback on the HPG axis.
High GnRH.
High LH and FSH.
What is azoospermia?
Absence of sperm in ejaculate.
What is oligospermia?
Reduced numbers of sperm in ejaculate.
What investigations may be carried out to check for male hypogonadism?
LH, FSH and testosterone measured. If all low, MRI the pituitary.
Prolactin.
Sperm count.
Chromosomal analysis.
Look at sperm under microscope to check numbers and motility.
How is male hypogonadism treated?
Replacement testosterone for all patients- increases muscle bulk and protects against osteoporosis.
For fertility, if hypothalamic/pituitary disease: gonadotrophins to stimulate testosterone release- give subcutaneous gonadotrophin injections to induce spermatogenesis.
Hyperprolactinaemia: dopamine agonist.
What are the endogenous sites of androgen production?
Interstitial Leydig cells of the testes Adrenal cortex (males and females) Ovaries Placenta Tumours
What are the main actions of testosterone?
Development of the male genital tract Maintains fertility in adulthood Control of secondary sexual characteristics Anabolic effects (muscle, bone)
