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Estrogen question......

Discussion in 'Step I' started by automan2, May 13, 2007.

  1. automan2

    2+ Year Member

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    When estrogen surges to create the LH surge prior to ovulation, what happens to FSH?

    It makes sense that when estrogen (+) feedback results in increased GnRH sensitivity of the AP and then BOTH LH and FSH would increase. If you look at any hormone level tracing, you will see this. BRS Phys explains it this way.

    HOWEVER....

    Goljan and First Aid say the increased estrogen negatively feedbacks on FSH? They both say this multiple times, but then show the standard tracing where FSH levels increase right along with LH levels!

    Can some expert sdner clear this issue up por favor.
     
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  3. SkylineMD

    SkylineMD Senior Member
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    i havent had time to double check but from what I remember, estrogen normally has a negative feedback control on both LH and FSH. It's only prior to ovulation that the feedback is reversed and stimulates LH and FSH. Why the switch occurs, im not really sure so maybe someone can clarify the - to + change
     
  4. rice_boy

    rice_boy Member
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    Ovulation does not occur immediately following the LH surge, but 34-36 hrs later. During this time luteinization of granulosa cells occur, which results in increasing Progesterone.

    It is the progesterone that is responsible for the midcycle rise in FSH.

    Don't ask me why the FSH then drops despite the rising P, cuz that's just like me asking why LH suddenly drops after ovulation (i.e. unknown).
     

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