PCOS

Question 1

What is the mechanism by which metformin improves infertility in PCOS?

Answer 1

IR leading to hyperinsulinaemia increases ovarian androgen biosynthesis and decreased SHBG synthesis, further increasing free androgens. Excess androgens and insulin cause premature follicular atresia and anovulation

Question 2

What is the mechanism by which clomiphene improves fertility in PCOS?

Answer 2

It blocks oestradiol’s negative feedback in the hypothalamus thereby increase the release of FSH and LH which promote ovulation

Question 3

What is the mechanism by which aromatase inhibitors are thought to improve infertility in PCOS?

Answer 3

AI’s block the conversion of androgens to oestrogens thereby reducing the circulating oestrogens. This reduces the amount of negative feedback at the hypothalamus > increase GnRH and FSH > promotes ovulation