Axis Flashcards
How does breast feeding prevent pregnancy?
Hypothalamus produces dopamine that inhibits prolactin production.
Prolactin has a negative feedback on the hypthalamus to prevent the production of GnRH -> decrease LH and FSH -> no ovulation
What Is PCOS?
are the symptoms, signs and causes of PCOS?
Polycystic ovaries are larger than usual, contain multiple small peripheral follicles with stromal hyperplasia (‘string of pearls’ around cortex of ovary).
Never get to the point of recruiting dominant follicle, so all follicles around the periphery are immature, thus never ovulate
Other possible diagnoses:
Hyperprolactinaemia
Androgen tumour of ovary or adrenal gland
Adrenal hyperplasia
What are the symptoms and signs of PCOS?
Gold standard, 2003 Consensus Definition, Rotterdam criteria
2 out of the following 3 features:
o Oligo-ovulation and/or anovulation
o Clinical and/or biochemical evidence of hyper-androgenism
o Polycystic ovaries on ultrasound (≥ 12 small peripheral follicles on each ovary)
Heavy irregular menstrual periods Irregular cycles oligo or anovulation Acne as a teenager and continued spots Weight gain Unwanted facial hair Baldness Enlarged ovary Insulin resistance
Hyperinsulinemia increases GnRH pulses but favours LH over FSH. Both LH and FSH are increased but LH is increased more so the ratio is 3:1 LH:FSH.
The LH stimulates the theca cells to produce androgens (estosterone) and the FSH stimulates the granulsoa cells to convert the androgens to estrogen. because there is more LH than FSH the conversion of testosterone to estrogen is inhibited and this results in excessive testosterone
Investigations Undergo a transvaginal ultrasound. LH, FSH (ratio) (3:1) Estradiol Progesterone Testosterone - high Prolactin - Normal TSH - Normal
What is the management and treatment of PCOS?
Management of PCOS
Loose weight
Medication to induce ovulation and reduce insulin resistance
Surgery to remove androgen producing tissue - LH and androgen levels fall
Medications
Clomiphene citrate - one tablet each day for the first 5 days of a cycle. It binds to estrogen receptors blocking the negative feedback of estrogen on pituitary and hypothalamus -> more FSH production -> normal follicular maturation -> ovulation
Metformin - decreases insulin resistance
How does annovulation cause heavy menstrual bleeding?
No ovulation -> no LH surge -> no rise in progesterone for 14 days and no drop in progesterone triggering menses. This causes the endometrium to continue to proliferate (estrogen continues to climb) leading to endometrial thickening
The endometrium can get so thick that it keeps sloughing away and growing in a continous cycle.
What are the signs and symptoms of premature ovarian failure?
Similar to menopause but under the age of 40.
Irregular ovulation and menses (reduced ovarian hormones).
Difficulty conceiving
Ovary has failed, low estrogen due to last few eggs, irregular ovulation is due to the last few eggs.
Bloods FSH: high LH: high Estradiol: low AMH: low Ultrasound: normal ovaries and uterus
What is premature ovarian failure?
Its definition is ovarian insufficiency leading to amenorrhea in women before age 40.
Follicles stop responding to gonadotropins.
The ovaries are not producing estrogen or progesterone. This causes in an increase in LH and FSH production because of a lack of negative feedback.
50% of women retain some intermittent ovarian function. Pregnancy possible.
How is premature ovarian syndrome caused?
No/few follicle sdue to degredation or born with few.
Follicles can’t function. Don’t respond to FSH or LH.
What is the treatment for premature ovarian failure?
Replace the hormones - estrogen and progestrone.
In vitro fertilisation - donor egg
