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n Obstetrics and Gynaecology Forum - Ovulation induction in women with polycystic ovarian syndrome : review
Women with polycystic ovarian syndrome (PCOS) have an increased incidence of World Health Organisation (WHO) group II anovulatory infertility.
The aetiology of the association of anovulation with PCOS is believed to be hyperinsulinaemia and is accentuated by obesity. Approximately 50% of women with PCOS are overweight and indeed there is evidence that even normal weight women with PCOS have increased intra-abdominal fat. More than 50% of lean women with PCOS are insulin resistant.
Hyperinsulinaemia and elevated leptin production from adipose tissue lead to increased ovarian androgen production by increasing ovarian theca cell cytochrome P450-scc and "cytochrome P450c-17" enzyme activity, as well as by increasing the frequency of luteinising hormone (LH) pulses, thus augmenting ovarian androgen production. This is in addition to the increase in serum free androgen levels, due to the inhibition of hepatic sex hormone binding globulin. The result is that serum and ovarian androgen levels are raised in association with impaired folliculogenesis. Methods employed to induce ovulation consist of weight loss, anti-estrogens, insulin sensitizers, gonadotrophins, laparoscopic ovarian drilling and letrozole.
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