Je. Hall et al., INSIGHTS INTO HYPOTHALAMIC-PITUITARY DYSFUNCTION IN POLYCYSTIC-OVARY-SYNDROME, Journal of endocrinological investigation, 21(9), 1998, pp. 602-611
Polycystic ovary syndrome (PCOS) is characterized by menstrual dysfunc
tion and hyperandrogenism in the absence of other known causes. While
the pathogenesis of PCOS remains elusive and is likely to involve abno
rmalities in several systems, there has long been an association of ab
normal gonadotropin secretion with this disorder. In recent studies we
have determined that 94% of women meeting the broad criteria for PCOS
have an increased LH/FSH ratio. Several lines of evidence suggest tha
t the mechanisms underlying the increased LH/FSH ratio in PCOS include
an increased frequency of GnRH secretion. Decreased sensitivity to pr
ogesterone negative feedback on the GnRH pulse generator may play a ro
le in this neuroendocrine defect. Additional factors which may contrib
ute to the low to normal FSH levels in the face of increased LH includ
e chronic mild estrogen increases and possibly inhibin. In addition to
these effects on the differential control of FSH, there is increased
pituitary sensitivity of LH secretion to GnRH. Both estrogen and andro
gens have been proposed as candidates mediating these effects. Superim
posed on these underlying abnormalities in gonadotropin secretion is a
marked inhibitory effect of obesity on LH secretion which may be medi
ated at either a pituitary or hypothalamic level. (J. Endocrinol. Inve
st. 21: 602-611, 1998) (C) 1998, Editrice Kurtis.